General

Oh and Zenonia 5 is good. The other Zenonias suck!

Did you jailbreak it?

Coin Dozer lasts a while until you can get infinite coins, Hungry Shark Evolution if you have enough space (its a big game). Fruit Ninja, Paper Toss 2.0, Draw Something.

If you like challenging games, get the Angry Bird games and try Hardest Game Ever 2 (warning it makes you rage). 4 Pics 1 Word and Candy Crush are also a good challenge.

Check the App store every 2 weeks or so to see if there are any new games with good ratings.

[*]Fun Run
[*]Plague Inc

running w/ friends

These are the ones I have but I realize that I stop playing them after like a week:
Fix It!
Subway Surfer
Little Things
Mini Golf
Scribblenauts ($0.99 not worth it, don't get it)
6 Numbers
Take it Easy
Glow Puzzle
Hardest 2
Tetris Blitz
Dumb Ways