Microsoft announced about upcoming games for Xbox Gold Live subscribers in August

Games list:

Portal Knights from August 1 to 31 (Xbox One)

Override: Mech City Brawl from August 16 to September 15 (Xbox One)

MX Unleashed from August 1 - 15 (Xbox One - Xbox 360)

Red Faction 2 from August 16 to 31 (Xbox One - Xbox 360)