Unhappy (Help) Games auto closing

i use temasek cm11 rom v124 and boeffla kernel

when i try to play a HD graphic game the game closes and goes back to the home screen. no force close or anything

i have this problem at many games for example real racing 3, Spiderman 2, Kritika..

I think its a ram problem but how can i solve it? i dont have many apps in background and i use greenify to clean it.

please help me