Android/iOS cross-platform multiplayer games

Hey guys, spent some time going through a few threads on here and tried a few suggestions but haven't really found much yet.

My partner and I are looking for some games we can play together online- sci-fi/fantasy/rpg is a huge plus but anything that's deeper than racing games/angry birds is on the table. He's on android and I'm on iOS.

So far the best we've found is dofus touch, which is heaps of fun but it's getting a little slow/Grindy for us and we'd like alternatives. Celtic Heroes made us both super excited when we came across it (I love playing support roles in mmos and so many recent titles don't have the option) but it's not cross platform and we'd be stuck on separate servers.

Tl;dr: Cross platform coop game (mmo huge plus). Really appreciate any help!