I haven't decided yet. In the end a platformer would take quite some work, in the graphics, and overall. I could make it an endless shooting game which would in time get harder and harder, and then just compete of high score. I have thought of a way to randomly spawn enemies and their "retro look" movement patterns, so i wouldn't need a level editor at all. Maybe you could even upgrade the ship while flying it... Because i dislike the way retro games get their weapon upgrades by directly assigning them from looting. It may override a good weapon you were used to with something bad, so i'd rather use a "ship builder" dialog you can open at any time.