With May beginning tomorrow, that means the Games with Gold lineup is changing out a few titles. Major Nelson revealed the lineup for May on his blog yesterday. Xbox Gold members can look forward to picking up Castlestorm: Definitive Edition and Pool Nation FX on the Xbox One. Xbox 360 owners will get Mafia II beginning tomorrow through May 15. On May 16th, that title will be swapped out of rotation for F1 2013, which will remain available until May 31.