I downloaded Dragon Coins today. I'm not sure what to think of this game. I was confused at first, but now I feel myself slowly getting addicted.
its part RPG and part SEGA Sammy Casino Simulator with some Microtransactions thrown in of course. but you don't need to buy the microtransactions to enjoy the game.
but yeah, its quite addicting. You collect monsters, go on missions and fuse them to level them up. You can also sell monsters too for gold coins. I know what I'll be playing now when I'm waiting for the bus ;D
but yeah, it's quite an enjoyable mobile game. you should give it a try if you think it sounds interesting. There is a whole wiki dedicated to the game and everything.
Oh i've also been playing Sonic Jump Fever, it's also a great game.