Seems like a fun game, but I have a few things to note.
1. It took me ages to realize that enemies sometimes drop hearts. They blend in really well with some of the backgrounds.
2. Checkpoints felt sparse at times—especially before difficult platforming sections. I wound up quitting the game right before the first checkpoint on the zone left of the crash site, right after the group of enemies right after the bounce-mushroom course, because I fell in the lava and realized I'd have to go through all that and then starting some from a completely different zone.
3. I am not very good at the game. I died a lot. On the bright side, this means I noticed an exploit any BUDD speedrunners could probably use—death sends you back to the last checkpoint with all progress intact. Useful for if you fall off the top layer (after reaching a checkpoint up there), and can save critical frames after getting the first attack drone thingy.