Interesting game, I really enjoyed the retro-theme especially with playing it on a (Microsoft?) game boy. It was fun although the enemies didn't pose much of a threat, I was able to run right through them and get to the end of the levels fast. I finished level 1 in only 14 seconds.
The only think I can suggest to improve on is making a death restart the level rather then kicking the player back to the main menu.
Overall super fun!