Ok, this is either gonna be loved or hated, but what if you made something like a campaign mode, where crazy monsters are on earth, and you work your way through levels, some of them have multiple little enemies, and some have large boss-like enemies. And it would be cool if as you go, you get new parts that you can add to your robot.
I know its not that easy to just make a new game mode, but right now the game's just the same thing over and over again, and even though it seems no one's gotten over it yet, I think adding game modes would help switch things up.