Triple Town is fantastic.
Can I recommend one? Middle Manager of Justice
Made by Double Fine (makers of Costume Quest, Stacking, Psychonauts, Brutal Legend, Iron Brigade) and was released on iOS only a few days ago. Think Game Dev Story but instead of making games you're hiring and training superheroes. It's got that trademark Double Fine charm in it's music and humour. Combat is similar to Costume Quest, stat based and in real time instead of turn based like in CQ.
There are in-app purchases but I haven't needed to use any yet though I will be handing over some cash just to show my support to Double Fine.