There is no controller support on Android mobile, while iOs does. Co-Op gameplay is extremely lackluster. Co-Op needs to be more integrative and have more to do, like raids and dungeon crawling modes that really bring friends together. New players wishing for new characters are gated and need to play through hours of story just to get the characters they wished for. This is why players are leaving. Content is fueled by each version update, but if players don't keep up, then interest dies down.