One of the unavoidable flaws of any Warhammer 40,000 PC game is that it cannot possibly please every fan. There are 14 different factions in the boardgame universe, each with its own roster of units. Each army has to be rebalanced in the transition to a videogame, which means that realistically, you can only add two or three races in any release. Chaos Rising – an expansion for Relic's Dawn of War II, though it does run solo – is even less ambitious on the surface, adding just the Chaos legions and their menagerie of daemons. At $30, it may be legitimate to ask whether it's worth it.

Gates of hell

The main campaign once again puts players in subsector Aurelia, but with a twist: planet Aurelia itself has re-emerged from the Warp, having vanished ages ago. It's not spoiling much to say that Chaos has come with it, and crushing the heretics is left up to the Blood Ravens chapter of the Emperor's Space Marines.

The first thing that might strike you in fighting Chaos units is that there's a much closer parity with the Space Marines. Both sides have relatively equal infantry, and you'll even see Chaos Dreadnoughts and Predators on the field. Distinguishing Chaos are their daemonic units and powers, making it more important than ever to concentrate fire on individual targets, such as a Sorceror.

It should be said that there's a greater variety of Chaos units here than in DoW1, including the likes of Plague Marines and Bloodletters. The Eldar, Orks and Space Marines have meanwhile gained a single new unit each - the Wraithguard, the Weird Boy and the Librarian, respectively - while the Tyranids have gained two, the Genestealer and the Tyrant Guard. The former may be around because of a few space hulk missions, which someone will hopefully use as an excuse to do a future standalone Space Hulk game.

Because Chaos Rising is an expansion, you can either import an old commander or start fresh; the former preserves any specialties you had, and tends to give you an edge in stats in general. Either choice puts characters at much higher levels than in the core DoW2, and so Relic has created new traits and wargear to work towards. As a rule these are quite welcome, granting even more power, and new weapon types like melta guns and lascannons. I had worried that the game would simply push the difficulty bar higher, instead of letting you enjoy a few of your perks.

Two roads

Equipment has a much greater significance within Chaos Rising in fact, as it influences units' pull towards Chaos. Arm gear tainted with Corruption and you'll gradually lose normal traits in favor of powerful Chaos ones. The flow can be reversed by using items with Redemption points, the drawback being that these objects can inflict penalties alongside any bonuses. Corruption levels ultimately determine which of five endings the campaign finishes with.

Corruption is more dramatically influenced through mission actions. Many missions in the campaign have objectives or conditions that can swing alignment; collecting Blood Ravens geneseed might add to Redemption, for instance, while leaving the Imperial Guard to die might lead to Corruption. In some cases, a character's mere presence or absence can have an effect. There are usually real risks to earning Redemption too, so the temptation of Chaos isn't just an academic one.

The new campaign is otherwise just as solid as the one in DoW2, perhaps moreso. Chaos Rising does seem to offer better rewards for tactics and strategy, although that could just be my experience coming into play. Be warned that some of the optional missions can be very tough - these can thankfully be retried as often as you like, and as before, you get to keep all of the gear and experience you collect on each attempt.

Multiplayer

Online play is also relatively unchanged, including two-player campaign co-op and team skirmishes for up to three human or AI characters per side. I can't speak much to the overall impact of Chaos in skirmishes, since a definitive answer would require a lot more matches under my belt. That being said the faction seems reasonably well-balanced, and its unique units - along with the new units for other factions - breathe a little more life into some otherwise static gameplay. I prefer the single-player in Chaos Rising, myself.

The game also includes Last Stand, a mode first introduced as a free add-on for DoW2. Three players, each controlling no more than two units at a time, are asked to survive against increasingly large waves of enemies in order to improve their score. The mode has its own persistent level progression, which opens up access to better wargear and minion units over time. This alone might prove addicting for some people, but it's shallow enough that it's clearly meant for casual sessions, when completing a whole skirmish or mission might take too long.

Emperor's judgment

There are two crowds for whom Chaos Rising will make sense. The first are people in love with DoW2's campaign style, which really hasn't been duplicated yet, and is only refined here with extra rewards and the Corruption/Redemption mechanic. The second group has to be diehard online gamers - the sort who are still playing DoW2 skirmishes every day, or at least every few days.

Chaos Rising is not an essential buy then, but it is easy to recommend. It might even be a good way of getting into DoW2, although it makes just the tiniest pretense at teaching gameplay, for obvious reasons. I suspect there will be at least one more expansion; personally my hope is that Relic will move on to new WH40K PC game, one a bit bigger in scope, if they don't grace us with a Space Hulk diversion first.