The base game is fine. But the problem is that PVP mode is busted due to the large amount of damage modders and cheaters that use lag as a battle tactic. It's a waste of time especially because it's a problem that is years old and the developer does absolutely nothing about it these days. So do not bother spending money on this app. You often see cheaters using 2-3 star characters with low rank equipment somehow besting your 7+ characters with S-rank equipment. The cheating is that bad.