a little basic but it has some potential. i really get some old school pc platformer vibes from it. i do think that if you're going to keep the shoot and gravity buttons on the mouse than there should be mouse aiming, but if you don't want to add mouse aiming than you should just move the shot and gravity buttons to the keyboard (i'd recommend the J and K keys) but thats just what i think.
looking forward to seeing more of this!