Nice job. I enjoyed running around with a little fat guy shooting colourful enemies. What would have made it even more enjoyable would have been a small enemy health bar above the enemies so I could see how many shots it took to kill them. Also as a rule of thumb it's much more satisfying having a powerful weapon that can kill enemies quickly. Go with high amounts of enemies that are easier to kill rather than fewer stronger ones. Given the time you did a good job, if you plan to develop it further polish up the artwork and definately make the enemy bullets easier to see. Also make the player flash or something when they get hit to show damange.