Yup, the main idea of the game was the limited buttons like the NES controller!
Viewing post in Schlafritter: The Sleeping Knight jam comments
Oh my... I actually have no idea what you mean with jumping with space, I've never wrote anything that uses the space key in the game, if you mean that in the epilepsy warning the game requires pressing the Enter key that was just it felt weird pressing J or any other of the action keys to continue.