Dangerously addictive but deceptively simple, Angry Birds lets you employ cartoon birds as weaponized projectiles in an escalating war against a posse of egg-stealing green pigs. (Don't ask.) Revenge relies on vectors and basic principles of physics, but the gist is to use a slingshot to angle an 'angry bird' at the smug little pigs. The real challenge? Putting your phone down once you've started.