I've bought loads of app store games now and some can be quite hit and miss. Here's what I love at the moment...

Super Monkey Ball - works excellently with tilt controls but a little expensive
Retro - You HAVE to get this, lunar lander/thrust type game. The controls (tilt) are excellent. Very challenging and cheap at 59p
DoodleJump - Rediculously addictive
Flightcontrol - very addictive game where you land aircraft at an airport without them crashing
2079 - top down shooter a little in the style of Geometry wars. The control scheme is great.
Let's golf - cartoony golf game, plays well but framerate suffers here and there. Tiger woods better but far more expensive.
Car Jack Streets - Original top down gta style game. Good value if it's still on offer (biggish download iirc)
Ivory - Well polished mahjong type game
Moron test - a good one for mates at the pub. Try it !
iFighter - vertical scrolling shooter
Wolf3D - a classic

Might add some more later.


Feel free to add your must have games. Retro is my current favourite.