I didn't expect it to be local multiplayer, that's great! Sadly I was only able to test it on my own so I can't tell how the whole experience with two people feels, but the game is really nice! Love the cartoony style of planets and the audio, the movement of Earth is really smooth and intuitive.
Is there a reason for earth controls to be distributed over the keyboeard like that? I think it might be better if you used "W" as forward or move the rotation to left and right arrow keys. It might be just me, but having full movement control with just one hand feels better and easier.
Hope you manage to put some more levels with some obstacles in there, nice work!!