Between March 1 and the 15th, the Tomb Raider reboot was available on the Xbox 360 for free, if you subscribe to Xbox LIVE Gold. Seeing as it is the 16th we need a new game, that game is BioShock Infinite!
Irrational Games' last installment in the BioShock series will be available until the end of the month on the Xbox Marketplace. If you have yet to give BioShock Infinite a try, it's a pretty good game. We gave it a 10/10, citing it as "a captivating ride that you don't want to end."
Basically, if you own an Xbox 360 and have Xbox LIVE Gold…you need to get this game.
If you have an Xbox One, BioShock Infinite will not be your free game. For the duration of the entire month, Xbox One users (that sub to Xbox LIVE Gold) have been and will continue to be able to download Rayman Legends and IDARB for free.