good job, ive been trying to do a pico-8 version of it, and flood fill is a nightmare, ive been stuck for two weeks with flood filling areas, and i still havent got it right
leaving trail surprisingly was the easiest part, and as for enemies i just made them rebound in the boders for now
would you be open to port your game in pico-8? i wish i had a guide to check how you did it