Interesting game play, but there are a few problems. First, but this problem has appeared for me the last few weeks with Newgrounds, is that i can't see the whole game in newgrounds window. But like i said, probably a problem on newgrounds.
The game itself is fine, but like another person here said, the graphics need an improvement. Some story would be nice too, since you went out of your way to create a ninja and "aliens", even if it is a silly story with comedy, at least something.