Team Meat is not one to shy from utilizing outrageous themes to embellish their games with. Perhaps, even those who have observed the founders of Team Meat for some time may have the impression that they are focusing their creative processes to increasingly outrageous themes for their games to build up the hype needed to raise their profile. The Binding of Isaac would not be dispelling this notion any time soon.
The premise is perhaps the most significant aspect of the game, and also happens to be the most contentious. The game starts itself – every time that it is launched – with an introduction to Isaac and his mother, as well as the abusive deprivation that his mother subjects him to due to her fanatical urges to please this game's version of God. When his mother eventually became homicidal, Isaac has to escape down into the depths of his home's basement, which he has not been to before and which hides horrifying secrets, as well as many parodies of biblical objects.
Here is perhaps where the squeamish or otherwise easily offended would stop playing and decry the game as hideous. It is indeed hideous, despite its cartoonish graphics (courtesy of Edmund McMillen's artstyle), but to those who perceive games as no more than entertainment products and their premises as mere fiction, this twisted parody of the biblical Binding of Isaac would seem to be a breath of fresh air (sort of) to those who are tired with the usual story designs that dare not explore unspoken/informal taboos.
For such players, they would notice that the story is also presented as possibly a product of Isaac's imagination; this would be apparent from the game's use of sketches and animations on notepads to present the main menu of the game and some of the cutscenes in the game (which in hindsight, is meant to seem surreal). That the game designers had not seen fit to concretely portray that what happens in this game has truly happened to Isaac can be a source of amusement.
Upon starting the game proper, the first thing that the player will notice is Isaac himself. If not for the game's cartoonish artstyle, it would have been obvious that he is a naked child forced to run around in unwholesome dungeons filled with evidently hostile and grossly deformed creatures, likely children themselves.
Isaac is depicted as always crying, which is, in a twisted way, fitting, considering his plight. However, perhaps as a parody of a certain other biblical story, Isaac's tears are weapons that can harm most of the denizens of the dungeons. He merely needs to blink in the direction of enemies (but not every direction; this will be elaborated later) to send some (thematically outrageous) balls of tears their way. Other than firing tears (and other projectiles, as will be described later), Isaac's only other form of readily available defence is to simply run away; almost all enemies in the game can harm Isaac upon contact.
However, all of the above is easier said than done. The game does not have much in the way of tutorials. The very first room that Isaac enters has murals on the floor that inform the player of the default control inputs and what they do, but there is little more hand-holding. This is of course a trait of Edmund McMillen's games, as fans of his products would point out, but to the players who are not fans, learning things the hard way either leads to the realization that they have been wasting time doing things the wrong way or that they have wasted a lot of opportunities because they had not been informed of the tell-tale signs of the presence of these.
Neither is a pleasant experience initially. The player's response and attitude towards the game after learning these will depend on how much the game has impressed them; it would be difficult to refute the possibility that the game may well alienate players who do not like realizing that they have been wasting time and opportunities. On the other hand, the game has a lot to impress – and disturb – the player with.
It would not take long for the player to realize that vanilla Isaac is just too weak for the challenges ahead. Therefore, the player has to "upgrade" Isaac with the game's take on power-ups, which are represented in the form of "special" items in this game. To describe the power-ups in a section of their own would be to understate how much they can change up the gameplay, so they will be mentioned when appropriate as the aspects of the gameplay are discussed.
However, it has to be mentioned here first that almost all of the power-ups in the game will alter Isaac's appearance. Isaac's sprite is composed of multiple components, such as his feet, torso, arms, eyes, mouth and head; the default sprites for these can be swapped out for those associated with the power-ups, usually much more hideous ones. Isaac's sprite also has invisible anchors for other sprites to be latched onto it, thus allowing him to don things like silly hats, among other much more ludicrous things.
Examples of these changes to Isaac's appearance will be mentioned when some power-ups are decribed as examples later. Regardless, it has to be said here that it is likely that Isaac will look very, very far removed from the naked, crying child that he was at the end of any successful game. In fact, considering how Isaac brutalizes himself with seemingly mundane items like coat hangers and how eager he is to utilize items of unholy origins, one would wonder whether his mother's eagerness to violently absolve him of his "sins" is justified.
(It is also worth noting here that Isaac eagerly announces that he has retrieved a special item by holding them up above his head in an obvious tribute to the Zelda games.)
However, not all changes of Isaac's appearance will be retained throughout a run; a power-up that changes the looks of one particular component of Isaac's sprite will supersede any change of that component that had occurred earlier. There is no way to retain visual changes that the player likes.
As a naked and terrified child with lethal tears, Isaac may seem problematic to use initially, especially for new players. He can only fire tears in the four cardinal directions, as opposed to many of his enemies, which can fire projectiles in his general direction. There can be some versatility to be had from the importing of some of the momentum from his movement onto his projectiles, but attempting to angle tears diagonally towards targets is a very clumsy solution. This also tends to expose him to attack, if he has to come out of cover. His tears can cause knockback on incoming enemies, but by default, the knockback done and his rate of fire is not enough to keep them at bay.
However, with the right upgrades, the weaknesses of Isaac's default attacks can be overcome, or eliminated altogether. Certain power-ups increase the damage of his tears, his rate of fire, the speed of his tears and their range, to cite the more mundane of improvements. Most of them tend to alter the appearance of his tears too. For example, the Blood of the Martyr increases the damage of his tears and turns them red, in addition to adding a halo of thorns as a hat for Isaac.
There are ceiling limits to these statistics, however, which had been implemented to prevent Isaac's tears from becoming too overwhelmingly powerful. These limits are not represented numerically, which can be a disappointment to players who want to meticulously measure and compare upgrades, but the graphical representation that are meters and bars should be enough for the purposes of keeping track of these statistics.
Not all upgrades contribute to the raising of these statistics, however. Some of them exchange one stats for another at various degrees. For example, the most extreme of these is Number One, which gives Isaac maximum rate of fire but completely minimizes the range of his tears, or more precisely his pee as he now fires projectiles from his groin instead of his eyes. (It also happens to stop his crying and makes him smile all the time, as if emphasizing the drastic change.)
Such "upgrades" are perhaps where the game stumbles in terms of user friendliness. The player has no way other than to depend on his/her own experience (and third-party Wikis on this game) to get an idea of what items do; items that appear in the game world not have anything other than their sprites and names to suggest to the unfamiliar player about what they do when obtained.
Returning to the methods of attack available to Isaac, there are also power-ups that impart additional properties to Isaac's tears, or completely replace them with something else. For example, there is the Spoon Bender, which grants slight homing capabilities to Isaac's tears and turn them purple. Another example is the Technology upgrade, which turn his tears into laser pulses.
However, some of these upgrades can be so useful that they become rather overpowered, because enemies had been designed with the player only having access to at least tears in mind. Therefore, these other forms of attack allow the player to exploit their weaknesses a lot more easily.
One example is the Brimstone upgrade, which has been downgraded a few times, yet is still one of the most powerful upgrades in the game largely due to how it simply bypasses any monster's defences and reaches from one side of the screen to the other without being blocked by anything, possibly hitting multiple targets; of course, it has to be charged up before it can be fired, but the player can keep a full charge and move around without much of a problem, thus allowing the player to start a fight with a blast that can cripple the opposition before they can do much of anything. (That the Brimstone upgrade turns him into what appears to be a raging imp further emphasizes the massive improvement in his firepower.)
Of course, one can argue that these upgrades are rare, but seemingly more balanced upgrades can be mixed with others to create a very potent mix. This is possible because Isaac can retain most upgrades (even if he loses the cosmetic effects of these items), without any limits on the number of upgrades that he can have.
For example, there is Cupid's Arrow, which grants his tears the ability to bypass enemy defences, such as hitboxes with facings that could not otherwise be penetrated by his default tears. This upgrade removes the knockback property of his tears as a consequence, which on its own is a pretty good balancing drawback. However, when paired with the Oujia Board, which gives Isaac's tears the ability to bypass obstacles (and turns his face hollow and ghastly), his tears become the rapid-fire equivalent of Brimstone.
Initially, Isaac can only walk around on his tiny two feet, just slightly faster than the monsters that would chase him in the early levels. Eventually though, there would be enemies that can move rather fast, or have sudden bursts of speed that can catch an inexperienced player off-guard. Obstacles like pits and walls of rocks can stop his movement, or otherwise hide goodies from him, and there are enemies that can pass through or circumvent these obstacles where Isaac cannot.
Fortunately, there are power-ups that change his method of mobility and perhaps even give him an edge . There are the more mundane of items that increase his speed of movement, such as the Wooden Spoon, which increases his speed after Isaac has apparently bruised himself all over with it. However, being speedier is not always a good thing: the maximum speed and the speeds two levels under that make Isaac more difficult to control, especially when attempting to dodge both enemies and hazards at the same time.
Then, there are more exotic ones, such as The Virus, which gives enemies who try to collide with Isaac a taste of their medicine (pun not intended) (and turns Isaac all diseased and scabby).
The most potent – and most imbalanced – of these mobility upgrades are those turn Isaac into a flying creature. He becomes able to fly not only over obstacles, but also over hazards like spiked floors and pits. Considering that not many enemies have such abilities, this can give the player an overwhelming advantage. The imbalance is further compounded if the player character has upgrades to his methods of attack that bypass obstacles and the hitboxes of enemies, like the aforementioned Brimstone, thus making Isaac capable of moving and attacking anywhere.
Tears and other things that Isaac may shoot out of his eyes, mouth or groin are not the only methods of attack that he has.
Bombs are one of the most utilitarian tools in Isaac's arsenal, though they can be risky to use as Isaac is not immune to their blasts when they detonate. When laid down, bombs do not just sit where they were. Instead, they can be shoved around by both the player character and enemies. Theoretically, this feature could be used to push bombs out of cover to hurt any enemy that has pinned down Isaac, but this rarely happens and even if it did, it is because the player made mistakes. Perhaps they can be shoved up to a certain turret-like enemy in the game, but that enemy is immune to bomb explosions when it has hunkered down underneath its shell. Moreover, bombs laid by Isaac have too much inertia to be reliably pushed around.
In other words, Bombs are just too cumbersome to be used other than to bomb a static spot. The feature to move bombs around is more of a nuisance than a useful contribution to the gameplay.
Instead of using Bombs to damage enemies (which are generally too mobile to be efficiently defeated with bombs), the player will be using them to blow up obstacles such as rocks that are blocking the player from reaching certain goodies. However, Bombs are not very common drops (unless the player gets lucky; there will be more on the factor of luck in this game later), so the player will have to do some simple cost analysis to decide whether the goodies that the player can get after blowing obstacles away are worth the expenditure or not.
Bombs are needed to destroy walls that lead to Secret Rooms (more on these later), but even then there are upgrades that render this unnecessary, such as the X-Ray Vision upgrade, which gives Isaac silly glasses that automatically reveal entrances to Secret Rooms. (It has to be mentioned here too that the X-Ray Vision also allows an exploit that lets the player leave rooms before clearing them, if they happen to be adjacent to Secret Rooms; there will be more on clearing rooms later.)
Bombs are useful for boss fights against bosses that are static (and a specific, gluttonous boss), but using Bombs in addition to primary attacks requires more finesse from the player, who also has to focus on dodging the dangers that the boss will pose. Moreover, there are always the inherent risks of accidents. (Some bosses have hitboxes that can move the Bombs around as well as Isaac can.)
Ultimately, if the player can get alternatives to the above-mentioned uses of Bombs, they are reduced to something that the player uses to blow up things that they do not like or no longer need, such as the coin-consuming NPCs and machines in the game (more on these later). In other words, when they are no longer useful to a player who has a heavily upgraded Isaac, they are no more practical than gag items.
Consumables items that the player character can collect include the aforementioned Bombs, Keys and Coins. The latter two are more useful throughout any run in the game than Bombs would be, regardless of how powerful Isaac can become.
Disposable Keys are needed to unlock Treasure Chests and Rooms (more on these later) to get at their (usually) beneficial contents, as well as to unlock the Shop Room (more on this later too). This is especially so in the early levels, where said locked objects and areas are more numerous than in later levels.
The designs for Keys would have been satisfactory, if not for how the player spends them. To spend a Key to unlock something, the player needs to have Isaac push up against a locked object, upon which a Key will be removed and inserted into it. This would not be a problem with locked Rooms, but with Treasure Chests it can be so; they can spawn from slain monsters and certain destroyed objects, so if they perish near chokepoints, the player can't go through them without bumping into the Chests and unlocking them, thus spending a Key.
Coins are of course the game's representation of money. These come in two common denominations, the penny (one coin) and dime (five), though higher denominations exist in the game as special items.
Coins can be obtained as loot drops from defeated monsters, as loose change lying around in rooms (usually blocked by obstacles), or as contents in chests, among other kinds of yields. They can be spent in a few ways, the most reliably productive of which is to spend them at Shop Rooms (there will be a bit more on Shop Rooms later). The goods sold are at least shown up-front along with their prices, though the goods offered are often random, and may even be awkward; an example of the latter is the Quarter, which gives 25 coins when purchased for often less.
Coins can also be spent at Slot Machines and donated to the NPC known as the Beggar. As to be expected of Slot Machines, the player stuffs coins, one at a time, into them in the hope that they can get lucky enough to have something beneficial pop out of them. The player gives the Beggar (who appears to lack legs) one coin at a time by simply having Isaac bump into him, and like the Slot Machine, he may provide a reward if the player is lucky, though he has more reliable payoffs than the more fickle Slot Machine. There will be more on Slot Machines and the Beggar later, as they are too significant to be considered a mere note when describing Coins.
Isaac's health is denoted by icons of Hearts. If he suffers harm, he loses at least one-half of a heart, and if he loses all, he dies; if the player does not have extra lives, it is a straight game-over (hence giving the game the description of a rogue-like RPG, though rogue-likes do not have the mechanic of extra lives). Therefore, Hearts would usually be welcome drops as these are the main ways to replenish or bolster Isaac's health. There are many ways to gain Hearts: they mainly exist as drops from enemies or room clearings, but they may also be spawned through activated items (more on these later) or the aforementioned Slot Machine and Beggar.
There are a few types of Hearts to be collected. Two of them are mundane Hearts that refill the player character's regular health, while the third is the Soul Heart. It is basically extra health of sorts, similar in function to the shields or armor in sci-fi shooters that have them, to use a convenient analogy: Soul Hearts are always expended first before regular Health, if they are available when Isaac is harmed.
However, despite being not as easily replenished as regular Health, there is no limit to Soul Hearts that the player can have. The launch version of this game has plenty of exploits that allow the player to farm Soul Hearts, leading to a player character that is virtually impossible to kill unless the player is deliberately careless. There have been fixes and balancing of course, but the lack of a limit remains, allowing a particularly lucky player to hoard a lot of Soul Hearts.
Perhaps disturbingly, Hearts can be spent just like Coins in return for goodies. The less risky method of spending Hearts is through Blood Banks, which takes away half a heart each time its front-face is bumped into and returns Coins in return; the player character's maximum Health is not (there will be more on Blood Banks later).
The other method, the riskier one, is to make deals with the Devil, whom the player character may encounter after defeating end-of-level bosses. The so-called Devil Rooms contain special items that often have to be "bought" by sacrificing maximum and current regular Health, meaning that Isaac can outright die if the player hasn't noticed that he is very low on regular Health; if he survives, he goes on with less maximum Health. Sometimes, items can be bought with the less risky loss of Soul Hearts, but this offer is only provided if the player happens to have lots of Soul Hearts.
The Devil Room can doubtlessly cause a lot of trepidation in players. Some of the most powerful upgrades in the game are offered here, but with the risk of a permanent death, players have to decide between gaining more power and having too little maximum health.
It has to be mentioned here that there is a glitch to be had if the player attempts to exploit an extra life that Isaac has. If Isaac dies from health loss through a deal but is revived with an extra life, he may or may not get the upgrade. This can seem disappointing to some players who are hoping to game the system.
Pills are perhaps the game designers' attempts at increasing the outrageousness of the game; after all, a child such as Isaac quaffing pills of dubious origins can project a rather disturbing image. Themes aside though, pills are by default rather risky consumables to use. They go into a slot on Isaac's person that is separate from other items, and can be used at any time for either benefits or detriments.
Each sprite of pills is randomly assigned one of the traits that pills may have every time a new game is started. This would not be a problem, if the effects of a pill that the player has encountered for the first time during a run are not obscured, apparently deliberately so by the game designers. This means that the player has little choice but to try out a new pill that has been discovered to determine its effects, thus risking any adverse consequences it has or possibly wasting its benefits, if it happens to be benign. This can be amusing, but also understandably frustrating.
However, certain upgrades circumvent this rule, such as the PhD, which gives Isaac a surgeon's mask and makes identification of pills nearly automatic, even if they had been encountered for the first time; moreover, this power-up switches the effects of pills that had been identified as bad to beneficial ones.
Such designs for pills can pose a detriment to gameplay balance. Firstly, which pills are spawned is a matter of luck, so the player may have the misfortune of encountering lousy pills one after another, such as the useless ones that make Isaac look mentally challenged, or has the sheer luck of encountering great pills, such as those that increase statistics. Secondly, having the pill-altering upgrades gives the player the latter case for the spawning of pills, possibly tilting the game balance in favour of the player.
However, there are designs in place to prevent the player from benefiting from Pills too much. The most significant of these is that the possible effects of pills outnumber the sprites for Pills. This means that not all effects will be featured in a game. (Of course, this also means that a player can be unlucky enough to have all pills in a run to be of detrimental effects.)
Tarot Cards are items that share the same slot as Pills, so the player will have to decide on bringing one in lieu of the other, or simply spend them on the spot when convenient. Unlike Pills, which are named according to their effects, each Tarot Card has its own name that gives suggestions on what they do. There are Tarot Cards that perform simple things like conjure Hearts, such as the Lovers card, or mimic activated items, such as the Chariot, which is similar to the My Little Unicorn activated item (which temporarily turns the player character into a weird, invincible creature with a horn that can destroy enemies with mere touch).
It is worth noting here though that unlike some Pill effects, all Tarot Cards do not have the capability to harm the player character, at least not directly, so Tarot Cards can be considered somewhat more reliable throughout the game. Furthermore, Tarot Cards have a lot more offensive capabilities than Pills ever will. The consequence of such designs is that players are more likely to opt to bring along Tarot Cards instead of Pills.
Activated items can be best described as portable special items that can be used multiple times for generally temporary effects. These takes up a slot of their own on the heads-up display, with a meter of bars that show the charge that they have accumulated. All activated items will have a full charge after they are spawned into the game world, and will completely consume the charge to produce their effects. To recharge them, the player will mainly have to clear rooms to regain some charge; certain activated items charge faster than the rest.
Most of the activated items are useful, such as the ever-practical Deck of Cards which spawn Tarot Cards, though some of them are gag items of little usefulness, such as The Bean, which releases a very short-ranged blast of poisonous air that is just too weak for use in combat.
All of the useful ones would have been quite balanced, if not for certain special items that can accelerate the charging, namely the Battery and the 9 Volt (not to be confused with each other). The 9 Volt (which Isaac unceremoniously jams into his skull) always ensures that the activated item's meter will have two bars of charge even after being used, thus leading to an earlier full charge. The Battery (which causes Isaac to have bolts inserted into his neck a la the Frankenstein Monster) lets the player gain a bar of charge every 20 seconds while in a room, up to three bars, and to a maximum of 6 bars.
While there have been a lot of balancing fixes for these two items (especially the Battery upgrade), they can still be used for exploits, especially when combined with the X-Ray Vision; such a combo allows the player to accumulate unlimited charges by moving back and forth the Secret Room and a yet-to-be-cleared room.
Isaac does not need to travel through the dungeons alone. Perhaps in a tribute to certain shoot-'em-up and platforming games, the player character can obtain Familiars, which are generally floating spirits that either add to the player's firepower or give support like spawning Coins or Bombs. An example of the former is Brother Bobby, whose name supposedly hints that he is a relative of Isaac that has since turned into a spirit with an anguished face and the capability to fire tears (or perhaps spit) of his own. An example of the latter includes the Sack of Pennies, which will spawn a Coin every few rooms.
The latter is also how the game pays tribute to games of yore that had the mechanic of extra lives. Certain familiars grant extra lives when they are brought to the player character's side, such as the very familiar and reliable 1UP mushroom, or the far riskier (but highly exploitable) Guppy the Dead Cat, which gives the player nine extra lives in return for having default maximum health jinxed to just one Heart.
The player character can only have one of each kind of Familiar, and the game will no longer spawn the special items that create this Familiar after the player has obtained it. There does not appear to be a limit to the number of Familiars that the player can have though, so a lucky player may be able to amass an entourage of Familiars, which can be an amusing sight as they strive to follow Isaac around.
However, there is an issue with Familiars; all of them have the same, fixed speeds, which is about the same as Isaac's when he has taken around two ranks of speed upgrades. If the player character is any faster, the Familiars often lag behind as the player character moves around. Considering that Familiars only fire their weapons when the player character does, and in the same cardinal direction, this can lead to a lot of wasted shots, reducing the utility of Familiars.
Satellites are similar to Familiars, but instead of following behind Isaac, they orbit around him at all times. However, they do not have attacks of their own; instead, they merely act as shields, blocking shots that would otherwise have come into contact with Isaac's hitbox. However, some of them do have the ability to damage enemies that come too near, such as friendly black Flies (that can only damage other Flies) or coloured Flies that can reach out a bit further to damage any kind of enemies. Satellites do not render the player invincible, but they do block shots when they are supposed to, making them a lot more balanced than the other power-ups in the game.
Another form of the Familiar is best represented by the example that also happens to be a tribute to Super Meat Boy, a rounder (and much slower) version of that game's protagonist. Initially, Meat Boy starts as a Satellite when the Meat Cube special item is retrieved, then turning into a hybrid between a Satellite and a Familiar when another is taken. When the third Meat Cube is obtained, the Familiar turns into a semi-independent follower that happens to be invulnerable and chases enemies around to damage them upon contact.
While this may seem very interesting initially, the player may soon discover that there are a lot of problems with Meat Boy and similar chaser Familiars. Firstly, the A.I. scripts for Meat Boy often appear broken; Meat Boy can be eagerly chasing enemies around, but may sometimes stand on one spot doing nothing; this also happens with the Dead Bird familiar that was introduced in one of the updates. Secondly, Meat Boy has a hitbox that also affects lit Bombs, making Bombs difficult to use as Meat Boy may run into them and push them away from where the player wants them to be.
It should be noted here that Pills, Coins, Tarot Cards, Hearts and Bombs do not sit on stone pedestals like other items in the game, though the latter can still be pushed around like the former (but they have a lot more inertia). Isaac retrieves Coins, Bombs and Hearts by simply moving up to them, unlike special items, Pills and Tarot Cards where he makes an impression of Link from the Zelda franchise. This would seem insignificant, but it should be noted here that the latter's animations prevent the player character from attacking or taking any actions other than moving momentarily, which can be a minor annoyance.
Where there are conflicting upgrades, such as upgrades that affect the properties of Isaac's tears or the ring of satellites that he can have, the most seemingly or potentially powerful of them supersedes everything else that is perceived as weaker. For example, the Meat Boy and Little Gish satellites always override the Fly satellites.
Considering how powerful some upgrades, upgrade combos and activated items can be, there are designs in place to somewhat balance them.
One of these designs concerns the factor of luck, which itself is not exactly the most reliable of balancing factors. There are hidden scripts in place to determine the probabilities of items appearing; generally, the more powerful ones have lesser chances of appearing. Factors like the depths of the levels that the players have gone to are also modifiers to said chances, as well as the amount of upgrades that the player has picked up. However, ultimately, the game still rolls dice behind the scenes and the rolls always have uncertain results, so if a player gets unlucky, all he/she will be getting are heart refills or money with nothing to spend or redundant upgrades. Conversely, if a player gets lucky, he/she will be getting splendid but overpowering loot.
Players who despise factors of luck very much would not like the fact that this game has them.
The other set of designs concern how much success that the player has in playing the game. Initially, many of the items that can spawn in the game world are locked away, especially the more powerful ones like the aforementioned Brimstone (and some of the items that would later come in one major update after the release of the game). The player will need to fulfill requirements that are hidden to the player before they can appear in the game world. These balancing designs are the more palatable of the two sorts.
For example, the Small Rock, which upgrades the damage of Isaac's tears (and which Isaac jams into his head, disturbingly enough), is only available after the player has accomplish the feat of destroying several loot-hiding rocks. Another example is Dr. Fetus (which is an homage to Team Meat's Super Meat Boy and which changes Isaac's appearance to resemble the antagonist of that game), which can only be unlocked by having five winning runs and which changes Isaac's tears to sliding bombs.
Having successful runs in the game also eventually increase the difficulty of the game, though this will happen after the player has unlocked certain very powerful items that may spawn instead of the lesser ones. The increased difficulty results in more enemies as well as more variations of the same enemies, usually with greater statistics or special abilities. Yet, while the game getting harder is a certainty, the player's chances of getting more powerful items to spawn is not as certain, so an unlucky player is still pretty much screwed, perhaps even more so than when he/she started playing the game.
However, the game does provide the player with chances (no pun intended) to have more control over his/her luck with the game. One of these comes in the form of the Lucky Foot (which gives Isaac an anklet, presumably retrieved from the severed foot that once bore it), which changes all pill drops into good pills and increases the chances of poo and fires dropping something when destroyed , among other benefits.
Perhaps the most reliable – and exploitable – method of changing the player's luck comes in the form of an item that can alter items that sit on stone pedestals or those offered in shops; this item was introduced in a content update. The player will have to fulfill more requirements to unlock it, but this item offers the player many chances to alter his/her luck by randomly changing items that sit on stone pedestals or in shops to other items. On the other hand, this can be exploited in many ways, such as switching the Small Rock to something else when it does appear from secret-holding rocks or the Dollar to something else when it comes out of a malfunctioning Slot Machine. This can lead to even more overwhelmingly powerful combos of upgrades.
While there is a factor of luck in the spawning of items, there is not any in how they remain in the game world. In fact, items that have been spawned into the rooms of the current level will stay where they are, regardless of how many rooms that the player character moves through. Handy icons will appear in the rooms in the map display for the current level, which will depict what loot is still there in those rooms. Yet, this is not exactly a perfect feature: if there is more than one kind of loot in the rooms, the icons simply overlap randomly or even supersede each other, making it hard to know what exactly is in that room if the player has forgotten. Still, that the items stay would be of great help and convenience to the player.
The Binding of Isaac has simple map designs, what with the emphasis on underground places, rectangular rooms of the same size and reliance on grids. However, to prevent the maps from being too predictable, the game uses procedural generation to automatically design and generate every new level that the player reaches. This is a technique that would not be unfamiliar to those who had seen it used in games since the first Diablo or even older games.
In this game, it is used to populate rooms with enemies and obstacles, usually with enemies well within the reach of the player character and vice versa. Entering a room that has not been explored previously will cause the doors to other rooms to be closed. To advance to other rooms, the player needs to clear the current room of all enemies, with the exception of a few that behave more like traps than actual enemies. Once they have been cleared, the doors will unlock and the current room will yield minor loot at the center, which is usually reachable. However, sometimes, the center of the room is full of obstacles, pits and spikes, making the loot inaccessible if Isaac does not have the necessary means to get them.
(There are more ways than just flying over to said loot, but to elaborate this is to present spoilers and hints that are not relevant to this review.)
Rooms will also be connected with other rooms such that they form corridors with branches. Once the player has realized this – which is not told to the player in any way, unfortunately – navigating the dungeons below Isaac's home becomes easier.
The only room that does not follow the usual rules is the Secret Room, which is often surrounded by many other rooms and of which there is only one per level. This is, again, not told to the player; a player who plays the game without getting informed about its designs wouldn't even know that Secret Rooms exist until he/she gains the X-Ray Vision upgrade or some other item like the Treasure Map that reveals the location of Secret Rooms on the map, or until he/she discovers them by accident, usually by unwittingly bombing the walls adjacent to these Rooms.
They usually contain simple but generally practical loot, the most common being Coins. Sometimes, it may contain Slot Machines or special items.
The Secret Room is also where one of the mini-boss fights occur. Incidentally, this very mini-boss would seem all too familiar to those who had yet to encounter a mini-boss fight in the Secret Room; to prevent any spoilers, who this mini-boss is will not be elaborated.
Anyway, this can result in a rather nasty shock for the unsuspecting player, as this mini-boss is one of the most troublesome mini-bosses in the game because it has attack patterns that can cover a large area (though the number of projectiles it can fire is rather lean) and the very annoying ability to steal Coins from the player with every successful hit. Of course, the player can recover some Coins by retrieving them when Isaac drops them, but this is an extra worry in addition to dodging the boss; some Coins are permanently lost anyway.
A significant complaint about the Secret Room is that the game does not retain any holes in walls that the player has made to reach the Secret Room after the player has left it. In other words, the player will have to blow a hole in the walls again if he/she wants to enter the Secret Room, which can be an annoyance.
The Treasure Room is perhaps the Room that players would welcome the most, as it does not pose any dangers and will always have special items on pedestals. To help a fledgling Isaac who has yet to turn himself into a monster, the first Treasure Room in any session is always unlocked; the later ones will always have locks and need Keys to be opened. To preserve gameplay balance, the Treasure Rooms no longer spawn in the very deep dungeons.
Shop Rooms, as mentioned earlier, generally offer items for sale, and these tend to be randomly picked. The level being played is a factor that influences the types of offerings, but generally the player has to depend on his/her luck. In other words, the Shop may offer useless crap, or very powerful items that the player just cannot afford; either case may lead to disappointment and a rude reminder that luck is a factor of success in this game. Furthermore, one of the items may be randomly chosen for a discount, and it may or may not be something that the player wants to buy.
There are some certainties to be obtained in-game though. For example, there is the Steam Sale special item (which in itself is a tribute to Steam, which at this time of writing is the only distributor that offers this game), which forces all offered items to be discounted to 50%.
It is worth noting here too that the Shop Room is an aesthetic tribute to the original Zelda games. It is also one room where the player may encounter a mini-boss fight instead of an otherwise safe place.
However, familiarity leads to skill, and eventually the player would be able to defeat this mini-boss more easily and profit from the loot that it drops (which ironically is a lot of Coins). On the other hand, another irony to be had is that the extra Coins cannot be immediately spent as the Shop Room has been replaced with a mini-boss arena, which can be a disappointing realization to some players.
Sometimes, Rooms spawn without any dangerous enemies (or spawn with pathetic creatures that still need to be cleared for the player to advance); these Rooms usually contain the Slot Machine, the Beggar NPC or the Blood Bank.
The Slot Machine, as its name suggests, is a game of chance; the player dumps coins in them and hopes for a return. If they are lucky, the rewards are usually Coins, though there may be other things like Pills, Hearts (more on these two later), Keys and/or Bombs (either lit or unlit). Sometimes, Slot Machines eject Flies, which are both a disappointment and a nuisance. There are a lot of permutations for these. Otherwise, the player gets nothing, which happens more often than not.
The Slot Machine may even malfunction and explode, upon which it may release some loot, usually Coins. There is a small chance that it may release an amusing special item that cannot be obtained any other way (and which has been mentioned earlier).
The Beggar NPC (also sometimes known as the Cripple, as it does not have any legs) has been mentioned a bit earlier; generally, the player keeps giving the Beggar coins, each of which may cause it to produce some items (presumably through one of its lower orifices), though the fifth Coin will always produce something. These are usually Coins, Bombs, Keys and Hearts, but there is a chance that he will spawn a special item and disappears. Overall, he is a lot more reliable than the very fickle Slot Machine.
Unlike the Slot Machine and the Beggar, the Blood Bank guarantees a return in Coins every time the player uses it. However, this is because the price it asks for is regular Hearts, which can be an unacceptable cost if the player is desperate for health replenishment. Perhaps in an odd twist of irony, the Blood Bank has a very small chance of exploding upon use, revealing another special item that can only be gotten through exploding machines and which replenishes a lot of health upon retrieval (though it gives the player character one of the ghastliest visual changes in the game).
To get down to the next level, the player has to defeat the boss of the current level. The boss is fittingly located in a room of its own. Bosses will be described later, as they are not unique to Boss Rooms. What can be expected of Boss Rooms though is that once the bosses are slain (usually in a torrent of exploding gore), the trapdoor to the next level will be revealed, together with a special item as a reward. The door to the Boss Room will also (generally) unlock, allowing the player to backtrack.
There is also a chance that a special room will unlock next to the Boss Room if the player has performed very well in the boss fight, i.e. not taken much of any damage. This room is none other than the previously mentioned Devil Room. It has to be mentioned here that the player only has one chance at getting anything in the Devil Room: leaving it often causes the door to the Room to disappear.
(The most recent update at this time of writing has also given the Devil Room a chance to generate a mini-boss fight instead of a demonic shop.)
In the deeper levels of the dungeons, there are so-called Challenge Rooms (also known as Arena Rooms), which has a chest or an item pedestal that will trigger a series of waves of enemies when it is opened or the item is taken, respectively. Considering the challenge that the extended battle has, the requirement to have full health before being able to get into the Challenge Room is understandable. There is no reward at the end though, thus giving the vibe that this Room behaves the other way when compared to how normal rooms yield loot when cleared. It would not take long for players to realize that a Challenge Room with a normal chest may not be worth the trouble, whereas a Treasure Chest (which requires a key) may yield something worthwhile (if the player is lucky); the special item is usually almost always worth the trouble, though this is a rare occurrence.
The Arcade Room may spawn at any level except the first, though this is not for certain. It would be a welcome sight to most players though, because it contains a Blood Bank, a Slot Machine and a special variant of the Beggar that will be described shortly, thus allowing the player to utilize any excess Hearts or Coins. Fans of the earlier indie games that Team Meat's founders have made (especially Edmund McMillen's) would also recognize the Easter eggs, homages and tributes in the aesthetics of this room (including its 8-bit musical soundtracks).
The Beggar NPC spawns in this room as a variant of the Slot Machine. Despite his resemblance to the dealer in a cup-shuffling game, it does not really matter which "cup" that the player picks after he has shuffled them; the player will ever only have one in three chances of picking the right one as the shuffling animations are always the same. The inexperienced player is not informed of this, which can be a disappointment when he/she does. However, unlike the Slot Machine, the reward, if won, is known before it comes out, but, like the Slot Machine, there are many permutations to the rewards.
Almost all rooms in the game will feature rocks and piles of poop. While the former are mundane things and act as obstacles as expected, the latter are not merely weak and lousy attempts at bolstering the unwholesomeness of the game; they act as destructible obstacles (though destroying a row of them would leave the player feeling a bit dirty), and also happen to attract black Flies, which are one of the most common enemies in the game.
Rooms may have hazards like spiked floors (which do not harm a flying player character) and bonfires, which damage anything that gets too close. There are also hazards that do not affect enemies at all, such as indestructible statues that fire projectiles at the player character and mobile blocks with spikes, though these become inactive once actual enemies in the room has been cleared.
Like the parodies of biblical matters, the monsters in the game are the products of the amusingly wicked minds of Edmund McMillen and his team. If not for their horrendous appearances, they would be almost immediately recognizable as fellow children or infants.
After several runs, the player will notice that enemies generally fall into several categories of archetypes, depending on their behaviour. The lower rungs of these archetypes are typically weak and mundane, but the higher ones, which are usually spawned in the deeper levels, have abilities that make them more troublesome.
The most basic, but the most numerous, are enemies that chase Isaac around all the time. They are easily avoided as long as the layout of the room does not hem Isaac in; if the player character can fly, they are completely helpless as long as the player character hovers over pits and other obstacles that they cannot reach. They are generally stupid, running into projectiles and hazards like bonfires and spiked floors. They also appear to have hitboxes that collide with each other, so they cannot clump together en masse. However, they do have A.I. scripts that allow them to predict when they might get caught in a bottleneck; the stragglers will take another path instead, giving the impression that they are smart enough to flank.
The later chasers have more tricks. They will not be elaborated much, as they appear to be well-designed enough to be an amusing if unpleasant surprise. One of them would be mentioned as an example though, as it is one of the most troublesome enemies in the game: the Globin. The Globin collapses into a pile of flesh when defeated, which may regenerate into a (slightly weaker) Globin, given enough time (which is not a lot); an alternate form of the Globin has it being even more troublesome.
However, all ground-bound chasers have a flaw: they may get caught in terrain features and have their A.I. scripts glitch, causing them to be rooted to the spot. When this happen, the challenge that they pose are drastically reduced.
There are also flight-capable chasers, such as aggressive Flies of various sizes. However, to balance their mobility, they are easy to knock around with projectiles.
The next major category of enemies can be considered the "loafers". They linger around, firing projectiles when the player character gets too close (thus acting like slightly mobile turrets). They are mostly manageable, but most of these enemies are flight-capable, such that they may stray onto obstacles that the player character's projectiles cannot pass through. This can be annoying when the player very much wants to advance to the next room. An example is the Pooter Fly straying onto rocks.
Next, there are behavioural hybrids between the chasers and loafers. These appear halfway into the game, and are almost always flight-capable, as such as the ghastly floating heads that are the Horfs and the even ghastlier "Babies".
There are even enemies that attempt to run away from the player, though these almost exclusively belong to the family of monsters that appear to have horrendously pox-ridden heads. They can be very troublesome to handle at times, especially the ones that spawn Flies to slow down the player, or the player can get lucky enough such that they run into hazards.
Turret-like enemies are not new, but the ones in Binding of Isaac are some of the most annoying to be had. The majority of them are the Hosts, creatures that hide under virtually indestructible skulls. They usually fire projectiles at the player character when he is nearby, but may choose to cower under the skulls indefinitely, or in cases of glitches, seemingly permanently. Considering that the player needs to clear a room to get out of it (at least without resorting to bombing doors), this occurrence can be very displeasing.
There are also enemies that appear to move about aimlessly and/or firing projectiles at random directions. Most of them act as spoilers, screening the more imminent threats to the player, though sometimes a room can spawn nothing else but them, which can lead to a time-consuming chase.
There are also variants for these enemies: the most common is the one that will charge when the player character crosses in front of them, thus making them more of a hazard than the regular loiterers.
There are many more enemies that cannot be readily lumped under categories according to common behaviour, which testifies to the amount of thought that went into the game. However, not all of that thought resulted in enemies that are satisfying to fight, as hinted at above already. There are some very frustrating enemies in the game, and the worst of them is a variant of the Hoppers, which are enemies that seemingly hop randomly around. This variant can perform an outrageous jump, landing at seemingly random locations or close to the player character to release projectiles in the four cardinal directions.
Bosses in these game are monsters that are generally larger, tougher and more hideous in both form and behaviour than regular monsters. The bosses are generally well-designed, having patterns that are quite manageable after the player has had enough experience fighting them. Not all of them would be described, but some notable examples would be mentioned to illustrate that they are not as typical as other bosses seen in many other games.
One example is Larry Jr., apparently a worm-like creature that slithers around at alarmingly fast speeds, but otherwise lack any sense of direction; it also releases a lot of poop from its rearmost section, disturbingly enough, which can stymie the player's attempts to stay out of its path. Older players would recognize it as a homage to Atari's Centipede.
Isaac's mother has been mentioned right from the start as the main antagonist, so it is fitting that Mom is one of the bosses. To elaborate more would be to mention unacceptable spoilers, but it should suffice to say that Mom is certainly not easy the first time around, and even experienced players would know that fighting Mom without hefty upgrades would lead to disaster.
After the player has become more experienced in the game, it will enable variants of enemies that appear to be palette swaps of existing enemies; they appear as colour-tinted and noticeably larger creatures. However, unlike typical palette-swap enemies, they are not just tougher variants; they may also behave differently, usually attacking more often. The player's reward for having to put up with these is that they are guaranteed to drop loot. However, it should be noted here too that even bosses can have palette-swaps, which make them even more aggressive.
The main player character is named Isaac, of course, though it is not known whether this is a figment of his own imagination, especially if the player considers the lore behind the other player characters that can be unlocked for play. They actually share the same sprite and animations as Isaac's, but with apparent differences like having hair (Isaac is bald) and may have headwear or eyewear as well. Yet, there are many things in the game to suggest that these are just alter-egos of the main player character.
These player characters start with statistics and items that are different from the default Isaac, but otherwise have the same capabilities; even their signature items can be obtained in-game. An observant player would notice that the best of reasons to play them is that they are needed to fulfill certain conditions to unlock more items. In fact, one of the (free) content updates allows the player to finally unlock a certain starting item for Isaac that makes him the most lucrative to use above the rest – ironically so, because before the update, he is actually the least attractive option once the rest have been unlocked.
A player that has experienced The Binding of Isaac for a while would have noticed that the game makes a lot of homages to once-popular games of yore, especially the original Zelda games. However, perhaps due to a stroke of ego, many of the homages are to Edmund McMillen's earlier games, such as Gish, Steve and of course Meat Boy. While fans of his games would be delighted, other more unfamiliar players would be left wondering what is exactly being referenced, if they are nought to dismiss them outright as products of demented minds.
As mentioned earlier, the game makes use of parodies of religious creeds and cultural matters for some of its content. However, even these tend to be Easter egg tributes to other well-known game franchises, such as the visual designs for Wrath, which is a mini-boss that more than resembles the protagonist of a certain game franchise involving a lot of cartoon bombs. Despite such ludicrous portrayals, it is doubtful that this game would sit down well with those easily offended, thus dashing its appeal.
To give a semblance of replay value, a lot of minor mechanics and special items are locked away until the player has had several successful runs in the game or fulfilled certain other conditions such as collecting a certain group of items. Each successful run ends in an animated cutscene that shows what has been unlocked (often followed by amusingly awful conclusions), while other conditions, when fulfilled, results in an announcement sliding into the screen that certain special items now have a chance to spawn into the game world.
However, as mentioned earlier, these conditions are not told to the player up-front; there is a Collection page that can be accessed from the main menu to show what special items have been encountered thus far, but these are depicted with very simple sketched icons that sometimes do not even resemble the actual sprites. They also contain little information other than the names of the items.
One of the most significant complaints to be had with this game is that there is no game-saving feature to be had in the game. Of course, one can argue that being a game with rogue-like elements and emphasis on fast-paced combat, this should not be a problem. However, considering the wealth of mechanics as had been mentioned above, a meticulous player could spend hours on getting an efficient playthrough; these hours are at risk of being wiped away if a game-crashing glitch occurs, or very bad luck rears its ugly head.
The game may appear to be able to run smoothly on most machines, given that it uses Flash-like code (which even posed a problem at the launch of the game, when certain hard-disk cleaning programs mistook the game files as trash) and sprite-based graphics. However, especially at launch, there were frame rate slow-downs when there are many enemies on-screen, more so when they are firing projectiles. This has since been fixed, but frame rate slow-downs can still occur due to the player character himself.
While such an occurrence is rare, the player character may amass so many familiars and tear projectile upgrades that the player can fill the current room with a lot of wet munitions quite easily, which can cause slow-downs. Although the player can moderate himself/herself, there is little incentive to refrain from putting as many projectiles in the room as possible.
The worst of the issues is the ones that are still unresolved. One of these, at this time of writing, is that there are control problems associated with tears that have been powered up by the Chocolate Milk special item (which has Isaac apparently spitting chocolate milk instead of blinking tears). While the player can still fire uncharged tears in addition to charging and releasing a more powerful shot, these have to be fired by rapidly tapping the attack button. The generation of projectile sprites and the torrent of control input appear to place a strain on the game, causing it to not only slow down but also to miss other control inputs.
The music is perhaps the most well-done aspect of the game, as it has very few if any flaws. Composed by Danny Baranowsky, a veteran of music designs for indie games, the soundtracks are mostly forlorn and ominous, which fit with the game's themes of madness and damnation very well; they can be rather depressing to listen to, however. There are more suspenseful and heart-racing tunes, namely those played during boss fights. Finally, there are cheery flourishes for successes on the player's part, as well as (even more) depressing electronic dirges for game-overs. If not for the album of the game's entire soundtrack on Bandcamp, musically-inclined players may be enticed to simply run the game just to listen to the music.
In conclusion, players looking for a game that is far, far removed from the usual sorts seen in the mainstream would be much delighted to play a game like The Binding of Isaac, and there is certainly addictively engaging fun to be had in collecting amusingly designed special items. However, unless a player is already well-smitten with this game enough to overlook them, he/she would notice that the game has a lot of minor technical issues and more importantly, the inherent difficulty in this game is over-compensated by the game's plethora of special items that can be combined into overpowered combos.