Definitely a pretty unusual mechanic and the game is built quite well around it. My only real gripes are that the control scheme is a bit needlessly clunky (but I understand it's 1 button instead of 2 to fit with the theme, and can't think of a better way to handle it with just 1 button), and that the floor tiles don't stand out well from the walls and exit. I'd recommend making them a darker color (PICO-8 color 5, the dark gray, might work well) so they're clearly distinct and don't fight for attention with the characters standing on them.