Restrictions:
Sadly, you made it obvious you didn't use the 84x48 screen limitation. You show it even on the cover. xD
Other than restrictions:
I think it would need a bit more explanation. I was just running around helplessly... Until I found out I can catch fireflies... And then I was running around helplessly. And the I found out I can switch to black... I think you get how it continues. Overall you did a great job on the visuals, they look neat. But this game needs some more gameplay mechanics.