Microsoft has revealed the two free games Xbox Live Gold subscribers will get in September as part of the Games With Gold program. The Games With Gold Program hands out two free games each month - one in the first half of the month, and a second in the latter half of the month. The games are only available within those time frames, so if you don't get them when they are available then you miss out.
The games for September are the popular collectible trading card video game Magic: the Gathering - Duels of the Planeswalkers 2013 (normally $9.99) – available between Sept. 1 and 15; and the popular squad-based tactical action game Tom Clancy’s Rainbow Six Vegas (normally $19.99) – available between Sept. 16 and 30.
Get Magic 2013 starting tomorrow - and remember - after the 15th you'll be out of luck if you don't download it...
Source: Xbox Wire