This month, Microsoft are offering 2x the usual free games.
April 1 - 16
Gears of War Judgement (29.95)
April 16 - May 1
Assassins Creed IV Black Flag(29.95)
Army of TWO: Devil's Cartel (29.95)
Pool Nation FX (14.95)
Child of Light (19.95)
FYI for the newbies;
All games need to be 'purchased' during the $0 period.
Xbox One games require Gold account to be maintained to access, 360 games are kept regardless of Gold account.
Xbox One games can be 'purchased via website or 360 dashboard prior to you actually owning the console, as long as you maintain gold account, games will be waiting for you when you get a XB1 console.
1 month codes will work for free games, 48 hour codes will not.