Expansion packs are something of a dying phenomenon. They're still being released of course, but they were really born of an era before downloadable content packs, or even broadband Internet. Now that it's incredibly easy to distribute bits of new content, it doesn't make much sense to box something unless there's a major addition.

In that sense it's remarkable that Dawn of War has had any expansion packs, much less a third one in the form of Iron Lore's Soulstorm. The series must clearly be doing something right to get to this point – that being said, it's also four years old, and so any expansion has to offer something dramatic to retain interest.

Witchcraft, heresy and mutation

The game starts off well or miserably, depending on your perspective. Its setting is the Imperial-held Kaurava system, where a Warpstorm has unleashed an invasion of Chaos forces. This being the Warhammer 40,000 universe though, virtually every other race or faction in the game has somehow become involved. As a result, a full nine armies - including two new ones - are thrown into a multiplanetary war of conquest.

This may sound new and unique if you've only played the core Dawn of War, or Winter Assault, but if you've played Dark Crusade, the Campaign mode in Soulstorm is practically identical. Players choose a single army and advance from territory to territory, laying siege to enemies while occasionally defending previously-conquered regions. Gamers can also upgrade their commander unit and his or her retinue, which is almost mandatory for fighting the stronghold missions that lead to victory.

The trouble is that most of these missions amount to one-on-one skirmishes for capture points, with unique objectives limited to the enemy strongholds. Even there Iron Lore has effectively cheated, as the Space Marine mission is lifted almost verbatim from Dark Crusade, down to some repeating dialogue. How they thought they could get away with that is a mystery.

If you've always enjoyed the Skirmish mode in Dawn of War, though, you'll probably like Soulstorm, since it doesn't tamper with the essential real-time mechanics. The game in fact adds some interesting twists to its campaign - because it's multiplanetary, only two or three factions are attacking each other at a given time, which creates a sense of breathing space. Some territories also have greater strategic significance now, as their Ancient Gates are the only means of traveling between worlds.

New facets

For veterans, the highlight in Soulstorm is clearly the new armies converted from the tabletop game, which continue Relic's policy of using dramatically varied gameplay mechanics. The Sisters of Battle are an all-female religious order, fanatically devoted to the Emperor; while superficially similar to the Space Marines, their unit spread is much more infantry-heavy, and concentrated around flame weaponry. They thus end up in close combat more often, although the Exorcist tank is now easily the best anti-infantry artillery on any side.

The Sisters are also dependent on a new resource, Faith. Though they can win fights without it, units like the missionary and the Confessor can turn the tide through special Acts of Faith. The Faith resource is generated partly by Holy Icons on capture points, but also by the very existence of some units, such as Seraphim squads. This leads to a unique dilemma, in which some troops need to be sheltered while still remaining within firing range.

The Dark Eldar, meanwhile, are similarly dependent on an exclusive resource, Souls. Souls are harvested from the dead, whether on the battlefield or from torture pits. Like Faith they're used to fuel special powers, the difference being that the Dark Eldar's powers can target any visible location on the map, making them especially dangerous.

The faction is otherwise strangely "soft" in terms of units, perhaps just slightly better suited for armored confrontations than the Sisters. The wisest thing to do with them is to exploit their flying platforms, which can hit an area and retreat before an enemy has time to react. As an especially sadistic bunch, the Dark Eldar additionally use weapons tailored to draining morale, which can sometimes cause frontlines to crumble if targeted properly.

My favourite of the new armies is the Sisters of Battle; regardless, it's mainly for their aesthetics and backstory, so both groups are a welcome increase in the diversity of Dawn of War.

Purgation

The last major change in Soulstorm is the inclusion of close-support aircraft, and it's mostly neutral. Each army gets one new vehicle, such as the Sisters' Lightning craft, or the Dark Eldar's Raven. The vehicles can't perform strafing runs though, nor can they drop bombs in the manner you might expect. They effectively behave like any other fast-attack vehicle in Dawn of War, the distinction being that they ignore terrain and can only be countered by units with the right weapons. I would say it's a wasted opportunity, except that the underlying engine is probably incapable of handling it.

Speaking of which, Relic's technology has finally made the transition from old to outdated; when compared with other real-time strategy games like World in Conflict or Company of Heroes, Soulstorm feels like an arcane artifact, one with blocky character models and absurdly low-resolution textures. It's certainly passable in the default view, but zooming in shatters any illusion. The engine is also missing any sort of lighting or physics simulation, which just by themselves would've made the game seem more relevant.

I hate to harp on negatives, but as of press time, Relic has acknowledged a bug lets the Sisters produce infinite resources during online play. I never encountered it in my own testing, but as people have imposed their own bans on Sister armies in some matches, multiplayer might as well be short one option until a patch is released.

Cleansing

To be honest, I went into this review expecting to write a more upbeat appraisal. I love the game, I really do, and I'd recommend it to anyone who's still playing Dawn of War. If you're not you may want to wait for the full sequel to the game, which is already in the early stages of development. Hopefully, that'll do Warhammer 40,000 better justice.