Before anything else; I haven't fully completed the demo (mostly because of my skill issue lol). Skill issue aside, I still have some problems other than "vidoe game 2hard4me :(".
The point collect sound effect is too loud / punchy, maybe try replacing it with something similar to the more silent clicking noise like in the official games? Or just anything more silent really.
Let us change controls!!! This might be an obvious thing to say but just let us use different keybinds, the default controls can be a bit weird imo (enter key pause button...).
Overall, good(?) demo from what I've played so far. Probably not for me but I hope my input helps :-)