XCOM: Enemy Unknown Demo

Although the game doesn't launch until October 9th, a demo for XCOM: Enemy Unknown is now available on Steam. This new addition to the franchise is a re-imagining of the original XCOM which was released way back in 1994, and they hope to recapture the tactical turn-based gameplay that made the series a hit. Unlike the first game, XCOM: Enemy Unknown will have a multiplayer mode as well as single-player, but as far as I know the demo doesn't have this feature. The download is somewhere around 6 GB.