Spacetime Studios has pioneered and pushed the success of MMOs for mobile gamers. Though I wasn't a big fan of their flagship title, Pocket Legends (primarily because of their lackluster avatar design), I got hooked on Star Legends for some time but found it quite repetitive in the process. Dark Legends was interesting because of its new combat and map system, but it didn't quite do it for me. Then they release Arcane Legends. Think Pocket Legends but better! It's free. Go try it.