The art and animations are nice, but the fun of a game this simple lives and dies on its balance, which isn't great here. With a single turret and only buying turret rate, you basically don't have any issues progressing. Even if it was better balanced, it would quickly get tiring anyway. With some different enemy types, unlockable kinds of turret, ability to replace buildings, more variety in the inter-universe buffs, and maybe a boss wave here and there, this could be really solid. Oh, and you can drag the health side-to-side, which I assume is a bug (but it doesn't seem to change the actual health value, at least).