Speaking at SXSW this weekend, Microsoft Studios corporate vice president Phil Spencer said that Xbox’s Games with Gold program (it's free monthly game giveaway for Xbox 360 - and eventually Xbox One) is "fundamentally different" than "other programs" (we assume he is referring the PlayStation Plus for PS3 and PS4) because it allows members to keep the games regardless of whether they continue to pay for a subscription or not.
PlayStation Plus program gives subscribers access to a collection of free games, but locks them out if their subscription expires. Microsoft's program allows Xbox Live Gold subscribers to download free games but does not take them away if a user decides to downgrade to a free Sliver membership. Spencer says that this has an impact on what games it can be include in Games with Gold.
Spencer went on to say that he is "playing a more active role in picking franchises that show up in Games with Gold, and I think you'll see something that feels at least more true to what I think Games with Gold should look like with the constraints that are there."
For March, Games with Gold’s free games are Sid Meier's Civilization Revolution and Dungeon Defenders. In February the company gave away Dead Island and Toy Soldiers: Cold War.