A demo for the third stand-alone expansion to Relic's venerable Warhammer 40,000 RTS series was released today, and is now available on Fileshack. The single-player demo clocks in at 1.12 GB.

Dawn of War: Soulstorm adds two new races to the mix, the Dark Eldar and the Sisters of Battle, for a total of nine playable factions. Aerial units have also bolstered the armies of all races, with the exception of the robot-like Necron.

All nine races will be enabled for play in the campaign mode, but only those who own the previous titles in the series will have access to the full selection during multiplayer sessions.

The expansion is currently set for a March 7 release on PC.

THQ today officially announced the next expansion pack for Relic Entertainment's PC RTS Warhammer 40,000: Dawn of War.

As previously reported, the standalone expansion pack is titled Soulstorm. Co-developed by Relic Entertainment and Iron Lore Entertainment for PC, it will bring with it a new campaign and two new payable races, one of which is the Dark Eldar. The other is currently unknown.

News of Iron Lore's involvement with the title does not come as much of a shock, as the Titan Quest developer recently told Shacknews that gamers could expect more action RPGs and RTS titles from the studio.

"In Dawn of War - Soulstorm, we've taken Games Workshop's epic war from one planet to an entire star system," said Relic general manager Tarrnie Williams. "Allowing gamers to play nine unique races, introducing air units and providing multiplayer achievements for the first time creates a tremendous amount of new and challenging strategic gameplay for all players."

Soulstorm hits stores in spring 2008.

Another expansion pack for Relic Entertainment's PC RTS Warhammer 40,000: Dawn of War is on the way.

Titled Soulstorm, the third Dawn of War expansion is confirmed to feature new Dark Eldar units and will likely cover the usual bases, including new maps, units, and single-player missions. The initial details appeared in a listing of the online extras for the October issue of PC gaming magazine Games for Windows.

Issue 11 of Games for Windows arrives in stores September 30. Expect more information then.