world runner: zenki the story could go like this after beating the final boss he was stripped of his power to return in order to leave the tower but that is pretty much when you choose a new class after maybe have him join like a guild depending on his class
true but you could make it in into the sequel game to but it could show how everything happened on how he got trapped in the tower and how he escaped but also leaving it open to roam around freely afterward but could you add some sort of skill tree with passive skills in the current game and the might be a limit to how far down it can go