Angry Birds. it gets pretty frustrating pretty often, but when it comes down to it, it's probably one of my favorite iOS gamesThe Sandbox is also really cool, but takes forever to get all the elements if you don't pay money (and you have to pay money to unlock most of the campaigns)both Ruzzle and Wordox are really fun imo, and even What's The Word can be kinda entertaining if you're bored (also they're all free)
jetpack joyride
Plague Inc.It's like Pandemic, but actually a game!