Tripwire's planning to let you all run free across the battlefields of Red Orchestra for a week.
Between August 2nd and August 7th, you'll be able to play the full game for free via Steam, and then make up your mind whether you fancy shelling out the $24.95 it costs for the full game.
Elsewhere, Tripwire says it's planning to have the booster pack it announced recently ready today, so you'll even be able to take advantage of smoke grenades and the like while you're testing it out for free.
Red Orchestra: Ostfront 41-45 is World War II multiplayer shooter - but whereas games like Day of Defeat: Source focus on arcade pace and tactics, Ostfront encourages more thoughtful, realistic tactics.
For more on the game, have a little look at the website.