I've gotta be honest, I really don't like "mobile" gaming. On cell-phones.
I've tried tons of times to pick up a game and play it on my phone, but I can't. I just can't. None of them really appeal to me, the quality is, well, cell-phone quality. The top games are typically pay-to-play. Sure you can emulate or pick up ported titles like Knights of the Old Republic, but I'm just gonna end up playing those on my PC or the original consoles.
I'd much rather have to carry around a 3DS and a Phone, than just my phone, if it means having to play.