the problem with the controls for me is click to draw then click to erase. backtracking should be easy. also, i shouldn't need to draw perfectly on the squares (especially if the game will be this tiny) so you'd need to make a system to guess what the player's intentions are (maybe paint the square on the general direction the player's pointing without crossing walls?)
but i know this is just a jam submission, i didn't expect a perfect game, i'm just giving you tips on your next one, and improving this one is great practice! it deserves it, such a cool idea