Hardcore game recommendations

I am a hardcore iPad gamer. I tend to play the games that take more time. I personally hate angry birds. Recently I've been playing Super brothers again, infinity blade and nova. Super brothers I've beat it 3 times. Infinity blade I'm on rebirth 30 level 57 and known on game center as a God King in the top 10 percent. Nova I haven't really been able to get into. I was wondering if anyone else knew any well worth hardcore games on the market. I know there are some on the app store. I am just wondering which I should spend my money on.