I was able to get up to Level 21 on my first time. Score of 5460. It's great for something that was made in two days, as it plays very well. There's a couple things you gotta consider in each level. Prioritize some of the aliens over others, and in later levels, be prepared to get out of the way of the firing squad that will all shoot at your spawning location, and be able to do a little "ring around the rosie" to take the shooters down. The game even heals you sometimes upon entering some new floors, either for a little or for all of your health.