Impossible Creatures' box-art already displays its greatest strength and greatest source of appeal; there had been stories and perhaps even games that featured unlikely hybrids of creatures before, but the image of a tiger crossed with a scorpion would be especially poignant in telling the beholder that the game intends to take this to the next level - and yes, crossing a tiger and a scorpion can be done in the game.
Impossible Creatures is a real-time strategy game that is developed by Relic Entertainment, which is the same developer that did the Homeworld series. Therefore, a player familiar with Relic's games can at the least expect gameplay designs and story-writing that are quite different from the typical norms in the RTS genre. The game does deliver these, but everything else about the game can be considered quite disappointing in comparison.
The game is set in a fictional version of the past where the calamitous Tunguska Event (which concerned a terrific explosion that leveled much of the Tunguska) is explained away with a fictional event brought about by a Russian scientist who is trying to change matter at the molecular level. Said event had tragic consequences for said scientist, but instead of being discouraged from continuing his profession, he switched projects instead and sent what is left of his family to the USA.
The new project was a success, but his past failure had consequences that spilled over to his academic reputation as well. However, his research did attract interest - of the kind that he would rather not have. A communique of distress is sent to the actual protagonist, asking for help to protect the scientist's research. The latter comes over to the archipelago of islands that the scientist is conducting his research on, and the game's single-player campaign starts proper from here.
The single-player campaign is the best place for a new player to start playing the game with, because its first few missions will act as tutorials, some of which will concern gameplay designs that are common to both the single-player and multiplayer segments of the game.
The most basic and fundamental gameplay design of this game is the mechanic of resources, of course; Impossible Creatures is an RTS game after all. Coal is mined from deposits that are peculiarly convenient to mine (the story writes off the backstory of this resource as a special trait of the archipelago of islands); it is then used as raw material to create carbon-based life-forms with, and to build and fuel power generators, which produce the other type of resource, electricity.
Coal is mined by comically portly caricatures of humans (though some characters, namely the main protagonists, are believably proportioned). Their presence in the game can be a bit awkward in a game about hybrid creatures, especially considering that they are especially vulnerable to being slain by the latter. Nevertheless, an observant player would realize that they are meant to emphasize the theme of the bizarre combination of animals.
(There are some in-game upgrades to improve their survivability, though these would be quite familiar to veterans of real-time strategy games.)
These resources will then be used to build the usual buildings that create units and implement upgrades for them that increase their attack and defense ratings and the likes. These are very rudimentary RTS game conventions and are not very remarkable.
If there is anything more remarkable, it is the mechanic of custom-designing units that can be placed into production slots for ease of creation. Two different animal species can be spliced together to create a custom unit that has any mixture of strengths and weaknesses of the parent two by selecting which body parts of either parent will go into the final hybrid creature. All of the weaknesses of the parent creatures cannot be eliminated, however, due to gameplay balance designs that had been put in place. (However, there still are powerful creature combinations that can be unfairly devastating, as will be elaborated on later.)
Of course, avid veterans of RTS games would point out that this feature is nothing new: it has been implemented in earlier RTS games such as Earth 2150. However, those earlier games still required the player to use certain aspects of units that must still be considered during customization, such as chases and the limitations of these that prevent the mounting of certain weapons on them in Earth 2150. Impossible Creatures allow the player to mix and match any pair of animal species.
Moreover, there is an army analyzing tool that the player can use to make automated assessments of the player's list of custom-designed units in order to identify the strategic strengths and weaknesses of his/her army. This tool is available in both single-player and multiplayer.
A gripe can be made here that only two animal species can be spliced together, despite the backstory of the DNA-splicing that could have allowed for more than two creatures to be merged together. On the other hand, this could be due to programming limitations, and even if it could be implemented, splicing more than two creatures together could have led to even more gameplay imbalance.
In any case, the single-player campaign presents this feature best, because it allows the player to replace already-designed units with new custom ones on-the-fly to counter the enemy with. Finding out the right combination that can demolish the enemy can be quite a treat.
Unfortunately, switching out already-designed units for new ones is not possible in multiplayer. At most, a player can create a slew of custom units to fit the player's chosen playstyle for the match, with virtually (and ideally) no idea of what the other players are doing. While the match may be unpredictable and some entertainment can be had from knowing what the others are bringing to the field, the players cannot switch out units for new ones to counter their opponents' with, which is a huge difference from earlier games with similar unit-designing features (namely Earth 2150).
Moreover, the match is pretty much over if a player managed to field units that can effectively counter the others'. This can actually happen more often than not, due to the certain imbalanced creature combos; this will be explained shortly.
The single-player campaign is not without complaints either. Enemy armies in the campaign usually start with fully developed bases that have plenty of resources and defenses, with virtually no weak points that can be exploited for quick victories. They are very single-minded, often sending the same kind of creatures even if the player has created the proper counters, along the same attack paths. Relic attempts to justify through portraying the commanders of these enemy forces as snobbish, overconfident fools, but this cannot hide the typical and somewhat lazy designs that Relic had used for the enemy AI in the single-player campaign.
In skirmish mode, the AI is a lot smarter, but it is subjected to the same limitation that players get in multiplayer. It can be beaten if the player is lucky enough to get hard-counters for whatever randomly generated units that the AI would use. Otherwise, the player will have to resort to exploiting its deficiencies, and it isn't really very smart as far as skirmish AIs in real-time strategy games have come so far.
The story design is of good caliber, as to be expected of Relic Entertainment whose portfolio includes the gripping plot of Homeworld. The roles of the two protagonists in the story are skillfully worked into the gameplay of the campaign.
To elaborate, new technology and buildings are not handed over to the player on a platter with a typically over-used excuse, so the player has to use the intellectually smarter of the two main protagonists to steal plans and blueprints from the enemy during missions. Furthermore, that the backstory of the archipelago of islands has the islands being populated by a diverse range of animals has the player using the other main protagonist to collect genetic samples from creatures that had not been encountered before; handy secondary objectives give an idea of how many new creatures that the player has yet to collect samples from.
The mysterious past of the second main protagonist also gives the player a "hero" unit of sorts that grow more powerful as the campaign advances, making him a very handy scout unit and bait to entice the enemy with.
Unfortunately, Relic Entertainment appears to have little experience fleshing out the individual scenarios in the single-player missions and designing the maps for these. As mentioned earlier, the player is often pitted against entrenched AI-controlled enemies that have to be defeated through attrition. The maps also tend to be composed of what are essentially corridors and wide-open areas connected by these; these are very old and heavily used designs in real-time strategy games.
There are some missions where the player does something else instead, such as buying the more scientifically-inclined of the two main protagonists the time to perform something that only she can do; these are more enjoyable missions, but they are fewer in number.
Fortunately, the player is rewarded with both in-game cutscenes and hand-drawn art that further the story in very intriguing manners (not unlike what was done in the Homeworld single-player campaign). These can be quite worth slogging through the blander of the missions.
Getting to the matter of gameplay imbalance, it has to be said here that this is especially detrimental to the game's long-term appeal because it happens to be a product of the game's strongest feature.
As mentioned earlier, the player can mix the DNA of two different creatures. While the weaknesses of both creatures will end up in the final product anyway, the player can still create a creature with strengths that are very hard to counter. For example, a Great White Shark can be crossed with a quick creature for devastating hit-and-run attacks, making use of the Great White's jaws to deliver powerful bites before running away; there are few official creatures with attacks or abilities that can slow down and counter these. Another example is the hybrid between the Blue Whale and a Lobster, but with the resulting creature being entirely the Lobster; the hybrid is thus a heavily armored, gigantic amphibious crustacean that is difficult to stop from thrashing bases down, especially if it is attacking from bodies of water, which can protect it from normal forms of detection.
Relic Entertainment does include measures to balance powerful combinations in more ways than the original animals' weaknesses can. These include raising their creation costs and increasing their creation times, as well as increasing their tier levels; creature creation buildings have to be upgraded to unlock the creation of these, thus preventing any player from swamping the opposition with powerful creatures during the start of a match.
Nevertheless, Relic Entertainment fails at designing effective counters against these powerful hybrids, which would have been more useful to address this imbalance.
What is more astonishing though is that Relic has not included more ways to better manage armies in Impossible Creatures, considering Relic's portfolio in Homeworld. In this game, the armies of motley beasts move like rabble, being not much more different from those in typical RTS games that emphasize strength in numbers and power of troops over formations and organization.
The multiplayer segment of the game does not resort to the usual game modes typically found in RTS games at the time, when many RTS game developers did not put in the extra effort to go beyond the norm. However, two of the official game modes would still be plenty familiar to RTS game veterans, namely a mode where the players vie to destroy each other's headquarters building and another that requires the player to destroy all of the opponent's buildings to eliminate him/her/it.
The third one gives every player a unit that is similar to one of the main protagonists in the single-player campaign. This unit is very tough, sprightly and difficult to take down, but taking it out eliminates the owning player from the match. Whereas the other two game modes may be won through the use of powerful anti-building units that can weather some punishment while doing their demolition work, this one can be won if the player can corner the other players' very-important-unit. In other words, this game mode is not fundamentally different from the others.
Impossible Creatures' multiplayer segment could have been more interesting if there had been a game mode that makes use of the game's greatest strength, which is the combining of animals. The official multiplayer maps are also unremarkable, though they contain more sophistication than the ones used for the single-player campaign, e.g. multiple avenues from one base to another that foster some strategic/tactical thinking.
Fortunately, Impossible Creatures does come with a mission editor and is quite receptive to mods, which would go some way in maintaining the interest of players who are enamored by its creature-combining mechanic.
A glance at the graphics of the game suggests that Relic Entertainment had chosen stylized and caricatured designs, which are more prevalently known as the "cartoonish" look. This lets the game create models with crisp outlines and cleanly-textured polygons, which are in turn easy to populate the screen with without severe frame rate drops. This is desirable, because players will often have to raise large armies of units, as is typical of an RTS game.
The greatest graphical achievement of Impossible Creatures also has to do with its greatest feature. A skeptical player may believe that combining two creatures of very naturally different species would result in a hideous creature with mismatching polygons. He/She would be half-right; the resulting creature is quite an abomination to behold, but the polygons that make up the different body parts from the different parent animals rarely have any technical hiccups such as severe clipping and mismatching sizes.
In fact, the polygons of the second parent creature will be re-sized to match the size of the model of the first one. For example, the claws of a scorpion will be enlarged to fit a hybrid that the player wants to be as large as a tiger. The transition from one polygon of a parent creature to a polygon of the other creature is smooth, in terms of polygon contours, though the transition of textures resorts to a lot of blurring and mixing of colors.
The movement animations of the hybrid creatures are dependent on whose limbs that the player chose as those for the final creature. The player can only consider the entirety of the final creature's set of legs (if any), so there won't be awkward movement animations that the final creature would have. The same can also be said for attack animations. These design constraints can be a bit disappointing to players who had been wishing for more freedom, but watching a sight as bizarre as porcupine/scorpion hybrid shooting quills in ranged combat and switching to claws or envenomed stings in close combat can be an entertainingly odd sight.
Most maps may be a mixture of wide-open areas and narrow corridors, but Relic has created a handful of terrain features to decorate them with; these include boulders and trees of various sorts, and the occasional abandoned dwelling. These match with the stylized look of the game, but they serve little function other than being eye-candy.
As to be expected, most of the sound effects in the game belong to the animal hybrids. However, although being hybrids, the calls that they make are dependent on the parent animal whose head that the player has chosen as the head polygon for the final creature; there may be other sounds that the hybrid may make depending on the body parts that the player has chosen for it, but if the player had been expecting a fusion of beastly noises, he/she would be disappointed.
The voice-acting in the game obviously only occurs for the human characters. There are actually very few unique voice talents in the game; these are used for the main protagonists and antagonists, but the secondary characters, such as the henchmen (which are the aforementioned human workers) have deliberately forced voice-overs, though these are difficult to associate with the pristine ones, fortunately.
Players who were enraptured with the soundtracks in the Homeworld games may find the ones in Impossible Creatures a bit disappointing as they are not really stirring and notably remarkable. Nonetheless, their more subdued and playful tunes fit with the stylized graphical designs and the themes of the game quite well.
In conclusion, Impossible Creatures could have gone a long way with its unit-designing feature, but Relic Entertainment did not take it beyond the usual RTS game tropes.