Bug: if you get three stars on "frenetic" it gives you credit for three stars on "normal," but if you get three stars on "hard" it doesn't give you credit towards your "frenetic" stars.
The different upgrades (head/body/etc.) all have different special bonuses, which is fine, but there should be some graphical way to see which one is best for my needs instead of having to hover over them with my mouse and read descriptions one at a time.
Very cute game. Please think a little more about how it should end when you reach your goals. (I would have expected at least a "congratulations" screen when I researched all the technologies.)