You should most definetly keep improving this! Maybe new skins? It doesn't have to be a creeper you know =/ It could be any mob, or if you want to add a real surprise you could even add Steve's head! Also different obstacles and new themes (Nether, End, sea, desert, etc.). You should also add some animaions, but don't overdo it =) Improve the hitboxes so that they will match the visuals. I hope this helps and the best of luck to you!