Fun, but very hard. I tried a bunch of times but I wasn't able to make it past the first level.
I found myself wishing I could walk around the platforms, like they were planets - oftentimes I would jump to the small edge of a platform, and then there was nowhere else to jump to (since the platform I just left had disappeared), and I couldn't move anywhere so I just had to tank a few hits until the previous platform reappeared.
Also, the boss's health is white on a light grey background. Maybe make that a different color.