A really fun romp with only one glaring flaw. The bosses are all over the place in terms of difficulty, with some being too easy and others being too hard*, however the entire rest of the game is almost exclusively a fun time, with great music and platforming action. I also really like Toc-Man as a villain. Definitely recommend.
* Pro tip: on King Galaxian you can fire more than once at a time by alternating between X & O. Believe me, this is a life hack you're going to need.