One of my favorite games to date, good job. But it still has a flaw that really bothers me. Sometime when Gunbot is hit, he starts running uncotrolably and normally that results into death from other enemies. Now this rarely happens but It's happened around five times within the first world.
Some things I would have liked to see is a character book of sorts that shows the name of the characters, bosses, etc. You had a nice design going on for your planet, it's a shame it wasn't named and such. Maybe, I'm the minority though. Also the music didn't fit well to me. I would have liked or more pop techno beat. Anyways.....great game!