This app was mentioned in 3 comments, with an average of 1.00 upvote
Kingdoms at war is free to play, buying in game items doesn't really help since it is mostly for appearance purposes, even though there isn't much to look at to begin with. It is an RPG and strategy game, very simple yet addictive.
Kingdoms at War: https://play.google.com/store/apps/details?id=ata.squid.kaw&hl=en