Just do what i do; give yourself a time limit for games. like if you want to study 3 hours, you can say "ill play until 5:00, study until 8:00, and if i think I'm fine, play more." If you don't feel you have the willpower to stay off until your preset time, i recommend hiding an essential cord or something on the roof, or under a couch or someplace difficult to get to. It helps a little to discourage you from going back.