I also don't understand the game fully.
Green=wall and Dark green=empty space maybe?
Design[3/5] Nice idea but feel like there could be a lot more to it. Also sadly with this game you need to read description on how to play it, instead of letting the player know the game using tutorials. But I agree that with 1 pixel it seems impossible to do.
Theme[5/5] You can't go any extremer than this.
Originality[5/5] Don't think anyone has done this before.