Welp, definitly some more levels. You could try to add some post-process effects! Try to also change player speed at x a little bit(love it down a little). Also, sope particle-effects would b dope, becose as einstein once saiD: Duh, everything is bedder with particles! You could also good in off, add some mooving platforms, and something like infinite-mode, with some procedular generation(it actually is not tht hard). Mayby also some simpy plot, becose plot make every game bedder. That's for start. :)