Age of Wonders II was a huge improvement and expansion over the first game; the new level of sophistication achieved can be tremendously overwhelming, what with its quite effective reconciliation between RPG and turn-based strategy elements.
Shadow Magic doesn't appear to try to repeat the same feat, however. This stand-alone sequel is more of an expansion to Age of Wonders II, and thus does little more than offer additional content but not technical improvements.
Shadow Magic is somewhat a continuation of The Wizard's Throne's narrative, though there appears to be a gap in the transition that may have fans of the series scratching their heads over why the protagonist of The Wizard's Throne is now out of action. The protagonist is now instead said person's compatriots in The Wizard's Throne, with the most prominent of them being the elven noble on the box-art, Julia.
The bulk of the gameplay mechanics have not changed much since The Wizard's Throne, so there won't be much elaboration on this. It should suffice to say that they still work very well.
In The Wizard's Throne, the first few campaign levels acted as a tutorial of sorts, but the player only has access to signboards that tell things in a fourth-wall-breaking manner, and which can be easily missed if the player is not observant. In Shadow Magic, the tutorial is better bound into the story, as it concerns the tutelage of a boy Wizard-to-be, who happens to have the privilege of having tutors guide his advancement.
Shadow Magic's most prominent contribution to the Age of Wonders franchise is the introduction of a new map layer, the Shadow World (some lingual versions of the game call this "Shadow Realm" instead), in addition to the original map layers of the Surface and Underworld. In this Shadow World, most units will suffer from Shadow Sickness, a de-buff that hurts their stats and prevents them from healing naturally (even Trolls). This puts them at a disadvantage against the denizens of the Shadow World, who are immune to Shadow Sickness.
Fortunately, there are spells that can be cast to ward off Shadow Sickness, and the Shadow Realm also has plants that fruit Shadow Berries, which can be conveniently eaten to provide temporary immunity to Shadow Sickness. (The campaign maps also have a lot of these trees, even more conveniently; unfortunately, this does appear to detract from the brevity of the designs of the Shadow Realm.)
Speaking of spells, every Sphere gains some new spells that either fill in strategic gaps in the gameplay designs of that Sphere, or introduce new tactical opportunities.
There are now spells that can be used as buffs when cast on certain units, while becoming de-buffs when cast on others. For example, there is the Life Sphere's new Holy Light spell, which is beneficial to good-aligned units, while being inimical to beings of evil nature; the Death Sphere's counterpart is, predictably enough, the opposite (if its name of "Unholy Darkness" would not suggest so already).
In the previous game, powerful high-tier creatures are more than likely to just roll over low-tier ones. In Shadow Magic, there are now spells that somewhat help bridge the power difference between powerful creatures and early-game ones. Chief of these is the Mighty Meek spell, which grants the recipient enhanced stats only when targeting and attacking units that are more powerful.
There are also spells that cater to last-ditch solutions. There is the Light Sphere's Martyr spell, which grant a unit doubled durability at the cost of certain death after the end of the battle.
Additions to spells that alter the map include the Death Sphere's Spider's Curse, which conjures webs and are very handy for holding back advancing enemy forces, the Air Sphere's self-explanatory Violent Storm and the Fire Sphere's also self-explanatory Wildfire. Conversely, there are spells that may make travel easier, or more difficult, depending on which units are travelling through a region affected by said spells, such as the Earth Sphere's Clear Terrain, which removes vegetation (e.g. forests) and roads and is a new cousin to the Level Terrain spell, and the Water Sphere's Mist Cloak, which can hide units in it but also restricts their vision. They are a bit more economical than the existing area denial spells from The Wizard's Throne, such as the Death Sphere's Evil Woods, though they are also shorter-lived.
While there were spells that affect the main map in The Wizard's Throne, there were few, if any, that affected the battlefield during the turn-based combat portion of the game. In Shadow Magic, there are now a notable number of such spells, which include the Air Sphere's Wind Ward that acts as a de-buff for all enemy units for a small number of turns, the Fire Sphere's Combustion, which cause all enemy units in the battlefield to burst into flames if they are not on fire already, Confusion, that is also of the Fire Sphere and causes some enemy units to suffer confusion every turn during combat, and the Water Sphere's Mud that slows down all enemy units. They can be a bit imbalanced, however.
The developers appear to have heeded the complaints of some players that in The Wizard's Throne, despite Heroes having abilities that allow them to evade death on the battlefield, they do not have many that protect them from being hunted down on the main map. After all, they can only exit the battlefield and suffer defeats from retreating so many times before the game takes away the option to retreat. In Shadow Magic, the player can have access to spells like the Air Sphere's Recall Hero, which whisks away the Hero to (hopefully) safety at the side of the player's Wizard.
Existing spells that are very utilitarian, such as the Earth Sphere's Concealment, have their levels and research costs, among other statistics, lowered to make them more easily accessible. Some other existing spells have been shifted from one sphere to another, such as the Water Sphere's Poison Domain, which is now the Earth Sphere's; this can change up spell builds, for better or worse.
(In return, the Water Sphere gains the Purifying Water spell, which makes all terrain features that contain water the ability to heal damaged units and remove some kinds of de-buffs. However, enemies may use these features as well as the player's own units.)
Units designated as mechanical may have vulnerabilities like weaknesses to fire and such, but there appears to be no other weaknesses that may balance against their immunity to many, many status effects. Therefore, the Water Sphere now offers a spell that is a hard-counter against war machines in the form of Rot.
In the previous game, the Cosmos Sphere has some powerful spells, but there were so few of these that the Cosmos Sphere tended to be used mainly as a supplementary to other Spheres. In Shadow Magic, the Cosmos Sphere has been expanded to include more spells so that it is now more of a sphere of its right.
New spells for this Sphere include Freedom, which grants the recipient cures and complete immunity to all mobility-affecting de-buffs; Magic Fist, which is an offensive spell; and Double Gravity, which takes away the flight advantage of flying creatures, to name a few notable ones. There are also spells that concern the movement of units to and fro the Shadow World and the Surface/Underground layers, which open up a lot of tactical possibilities.
However, there are a few small disappointments. One of these is Shadow Walking, which grants the recipient immunity to Shadow Sickness; it is not very useful in the story campaign, due to the plentiful Shadow-Berry trees in the Shadow World.
There may be some new spells that damage the balance of the game though. One of these is the Death Sphere's Animate Hero spell, which works like the Resurrect Hero spell, but brings back the fallen Hero as an Undead instead. This can give players who favor the Undead a rather overpowered advantage if they are able to slay enemy Heroes. Another example is the Seeker spell, which has a rather small mana upkeep cost to balance against its main benefit, which allows the recipient to completely ignore obstacles when making ranged attacks. This can make ranged-combat-oriented Heroes rather ovrpowered, especially in sieges.
(The aforementioned Freedom spell may also be quite overpowered if used on Heroes, though it is balanced by high mana costs.)
In The Wizard's Throne, gates have been made destructible by any unit, which is a game design meant to address a serious complaint in the first game. However, it still preserved the value of the gates as a way to delay the breaching of settlement walls. Yet, the introduction of the Earth Sphere's Crash Gate may make gates of any quality useless altogether. (Fortunately, it does not remove Wall Enchantments.) On the other wall, the new Regenerate Walls spell, which happens to be of the Earth Sphere as well, may help to counter the previous spell.
Some spells also appear to have some thematic issues, suggesting that the developer is at a loss at which Sphere some spells should be placed under. For example, there is the Air Sphere's Panic Attack spell, which invokes Fear in the target but which would seem out of place with the Air Sphere's themes.
Shadow Magic also feature new entries in the library of magical items. However, a discerning player may consider them a bit disappointing, considering that the bulk of them are actually item-based versions of the new spells.
In addition to new spells, there are also new races and new units.
One of the new races in Shadow Magic is the Syrons, who are a race that is indigenous to the Shadow Realm and are thus the only ones that are immune to the deleterious effects of the Shadow Realm. However, unlike the other sort of denizens of the Shadow World, they do not have the natural ability to simply bypass difficult terrain. In fact, they have few units that have movement methods other than Walking, not unlike the Humans. Yet, not unlike the Humans again, they can gain access to a powerful air-ship that can ferry around troops. They also have units that have a lot of variety in tactical value, which help ease their entry into the gameplay of the Age of Wonders franchise. For example, their basic unit, the Prospector, is capable of True Seeing; there is the Spellbinder, which is an anti-magic-buff unit; and there is the Giant Warrior, who is a particularly (and conveniently) large Syron that is a counter against walls.
One other new race is the Shadow Demons, which fulfill the high-fantasy archetype of demons and devils. They are also indigenous to the Shadow World like the Syrons are. As befitting their demonic nature, a lot of their units are hideous-looking, though they also have insectoid qualities; the latter were probably introduced to give a convenient sense of progression to the line-up of the units of this race.
All Shadow Demon units have varying levels of defense against Death magic and Night Vision, and more than a few have Magic Strike. However, a lot of them have weaknesses against lightning attacks, with the exception of the top tier unit, the Shadow Lord, and their high-level scouting/harassing unit, the Spirit.
The Shadow Demons' basic unit is the Larva, which surprisingly has a lot of special abilities (and some weaknesses), including one that allows it to turn into a higher level Shadow Demon creature upon reaching the Gold (or elite) experience rank.
Like the Syrons, the units in between the Larvae and the Shadow Lords have varying tactical values. Notable units include the Bombard, a beetle-like unit that can lob energy bombs over obstacles, and the hideous Harvester, which have the ability to devour units whole.
Their top tier unit, the Shadow Lord, can be quite overpowered though. In addition to having Magic Strike and Death Strike, it also has the ability to bring down walls. It can also Shadow Shift, allowing it to perform devastating hit-and-run attacks if the map is conveniently designed to allow this. It is, however, a very large target for ranged attacks and it does not have as many movement points as certain other top-tier units.
The last but not least new race is the Nomads, who are not really that new because they appear to be the successors to the Azracs in the first game. Like the Azracs in the first game, they have Middle Eastern themes to their designs. They have relatively higher mobility compared to units of most other races, but lower defense to reflect their disdain of encumbering armor.
Unfortunately, their high-tier units are not really impressive. The Pit Guard is a hulking brute with the Strangle power, but attempting to use Strangle successfully can be a pain as it is highly luck-dependent and there are better ways to Paralyze targets. Similarly, the Roc has its own special ability of Grasp, but its effects are also luck-dependent and the Roc may only use it a few times per day.
The existing races gain new units, which can be recruited through new race-specific buildings that also impart some bonuses to the settlement that has them. These generally introduce new twists to the gameplay of these races, or plug in gaps in their strategic designs.
The Archons gain the Saint, who gives the Archon army the ability to Resurrect at least one slain unit per battle, and this may include a Hero (who may have been used in a reckless manner); oddly enough, he has a weakness towards Death magic.
The Elves lack tough, line-holding units in The Wizard's Throne; the Faerie Dragon is too costly to be used as a line-holder, while the Iron Maiden is better off used as heavy cavalry. In Shadow Magic, they gain the Treeman, who like other high-fantasy sentient and mobile trees, is a very tough but slow unit. It also has abilities that make it especially useful for sieges, both on the offense and defense.
The Dwarves lacked a flight-capable unit, so Shadow Magic introduces the Gargoyle into their ranks. Considering the usual high-fantasy tropes for dwarves and gargoyles, having creatures such as gargoyles joining the race of stout, diminutive people are somewhat thematically odd, though the Age of Wonders canon does provide conciliation for this. Anyway, Gargoyles have a lot of immunities and flight capability, making them very, very handy as scout units.
The Chaplain fills in the Humans' lack of an anti-magic and True Seeing unit, as well as acts as a leader of sorts for parties of units.
The Halflings gain the Centaur, which further augment their reputation as a race that is difficult to use but offers rather rewarding gameplay if used successfully. The Tigrans gain the Beholder, which in gameplay terms, can be considered the floating versions of the Tigrans' Mystics, albeit with greater anti-magic capabilities.
The Draconians' Red Dragon is a powerful top-tier creature, but it can be rather expensive to maintain and losing one can be a rather painful blow to a player's strategic plans. Therefore, they now gain the Hydra, which has just as many hitpoints. While its other stats are lower (especially Movement), the Hydra compensates by having wondrous abilities like Spread Attack, which allows it to hit multiple targets in close combat, which is in turn further augmented by Double Strike. It is also capable of Regeneration, giving it staying power, especially if there are bodies of water nearby for it to take advantage of because it happens to have Swimming too.
The Frostlings get the Yeti, which can be considered a stealthier version of the Mammonth that is well suited for raids against towns that are located in snowy terrain.
The Troll returns in Shadow Magic, now being associated with the Goblins. They retain their Regeneration and spelunking prowess, and they are also able to hurl boulders, giving the Goblins an alternative to the use of Catapults.
The Orcs have long lacked a flight-capable unit. However, the developers' attempt to fill in this strategic gap may have caused thematic conflicts: the new Doom Bats can seem rather out of place in an army that is oriented around savagery and brutality, especially when their Life-Stealing and poisonous attacks are considered.
The Succubus returns in Shadow Magic too, becoming the Dark Elves' true flight-capable unit. However, other than this gameplay improvement, the Succubus doesn't seem to be any more than a thematic addition to the Dark Elves; as a high-tier unit, it has rather lousy stats.
The absence of a magician that is capable of raising the dead in the Undead's army in The Wizard's Throne was rather glaring, considering that such a character is an almost-given trope of the high-fantasy designs of undead factions. In Shadow Magic, this is corrected with the addition of the aptly named Necromancer. In addition to having abilities that reanimate corpses, he also has some magical and anti-magic abilities and also a not-too-shabby melee attack.
Units that are not aligned with any faction have also been added to or overhauled; these appear to enrich the game further.
The Parasite is the product of a certain insidious spell, which plants it into the unfortunate recipient. When its host is slain, the Parasite can emerge and attempt to infect another host, though doing so can be difficult as it is rather weak and tends to be a high-priority target by both AI and human players.
The Dragon Hatchling is a poor-man's Dragon, for the sake of those that need the maneuverability of a dragon but not its high costs. That said, there are also new fully-fledged Dragons, in the form of Black Dragons and Golden Dragons, the differences between them being the immunities and breath attacks that they have.
Some new units appear to be joke units, such as the Dire Penguin, which has hilarious designs and canonical portrayal, but otherwise have alternatives that may be more efficient to use.
In the first Age of Wonders, machines included units such as the Flame Cannon; these were removed in The Wizard's Throne, leaving the most fundamental of high-fantasy war machines behind. In Shadow Magic, the Flame Cannon returns, and comes together with its rime-based counterpart, the Frost Cannon; both provide machine-based breath attacks, which can be handy if there are terrain features that can funnel enemies into their range.
The Repeater Ballista is an upgrade over the regular one, being faster and having a denser volley. Finally, the Balloon provides a cheap option of aerial transportation, which was once the domain of the Humans.
Shadow Magic now has a random map generator to procedurally create maps that are different from those in the official package, which would be a boon if the player is looking for a somewhat different experience for every non-story session.
The Wizard's Throne has some minor but otherwise notable tributes to other high-fantasy genres, such as the Orcs' attitudes and designs, which is rather close to those in Warhammer Fantasy. Shadow Magic extends this by including tributes to some sci-fi franchises, such as the Infection spell, which may be a tribute to Aliens.
In conclusion, Shadow Magic does not appear to do what The Wizard's Throne did over the first Age of Wonders game, which is a massive and beneficial overhaul in gameplay. However, its contributions do enrich the already-rich gameplay a bit further.