Don't be fooled by the hawt animay wimin that are used in an attempt to get you to get a shitty game. As said by this guy
The community for it is actually pretty big and active and if you join now you can get some of the rewards they are giving out for their 7 million downloads event.
The only real gripe I have with this is that grinding is a pain until you get to the late game, and even then it's still a bit of a chore.
It's for Android and Apple but you can only play with people with the same platform as you.