I've got about 60 dollars worth of gaming apps so this was a hard choice.
Defender Chronicles
Tower Defense game; I've played about 5 different Tower Defense games, this is my favourite.
Inotia 2
RPG; I really enjoyed this game, although I admit I haven't completed it. I've also played the first Zenonia but I think this was superior, the second Zenonia might be better, but I haven't purchased it.
Angry Birds
Strategy; Who doesn't have this on their list? Fun, addicting, nice time waster.
Phase 10
Cards; I really enjoy this game IRL, so this was great. However AI makes stupid mistakes, no ability to play online or even pass and play options. No recent updates - it's been stagnating for awhile.
Need for Speed Undercover
Racing; I also have Need for Speed Shift which I do not like (what's with the arrows on the road?!) I find this racing game is far better with fun objectives.