5. Candy Crush Saga
Also Known As: That one you see dead-eyed subway riders playing day after day. There are many layers of insidiousness to this Bejeweled-like game that's become pop phenomenon: New levels keep getting added, hence you're always one step behind "winning" the game; a social element makes it ridiculously easy to play against friends no matter where you are; if you use up your lives, you have to wait 30 minutes to start another game, thus making it temporarily unattainable unless you pay to get back in. (In other news, this game is currently making its creators about $677,000 per day.) No wonder it's become the commuter-game equivalent of crack.