if you like old-school games as I do,
I suggest 100 rogues and Sword & Sworcery :
http://www.100rogues.com/ and
http://www.swordandsworcery.com/.
Then, do yourself a favor, jailbreak it (if you're still <iOS5), install iMame4all from Cydia, and all the arcade games of your childhood (if you're >~ 40 ysold) are at your fingertips... (buy yourself an iCade for Christmas of course - I did
http://www.thinkgeek.com/electronics/retro-gaming/e762/)