https://www.gamespot.com/articles/steams-next-free-weekend-games-now-available/1100-6454206/

Steam users can now play a couple of new games for free on PC. This weekend, players can try out a pair of Warhammer titles, including Warhammer 40,000: Dawn of War III, which is also available at a discount for the next couple of days.

Starting today, Steam users can download and play the real-time strategy game at no cost. The free trial gives you access to the full game and runs until Sunday, October 22, at 1 PM PT / 4 PM ET / 9 PM BST.