it's actually quite easy if you understand how to use the powerups. the yellow ones are typically so abundant that you can get all the time you need to complete the levels without a problem.
you get 1 star for a simple reason: it takes forever to reach anywhere near the edge of the stage due to how motion depends on distance from cursor. since all enemies appear at the edge of the stage, this means that a lot of time is spent watching your character slowly approach its target
close to good, but a few critical flaws:
1. enemy can spawn right on top of player without any warning; motion is too jerky; 3. something else I seem to have forgotten...