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Things to do/change:
Speed, can be changed in script.js; lines 8-19, change character.style.left
Change how big the game border is, expand if neet be, same with the holes etc., background, generally fuck around with the html if you want to
Maybe add a live score counter?
Change it to your liking, and keep in mind that this shit is bare bones, basically just recreated a version of what you sent me. If you want, de plagiarise it, chnage variable names, reorder shit etc.