This is a really interesting concept. In my mind it didn't quite work, but there are a lot of interesting ideas here.
The sparse, abstract storytelling is "neat idea, didn't work for me" in a nutshell. I only understand what's happening in the slightest because of the description on the page. There's a dead girl and a bunny rabbit and a scientist guy and spaceships and some kind of monsters that come in multiple sizes? The visual storytelling isn't enough to carry the narrative on its own, and there are no words to explain.
The crawling section was really chilling because of the shift in gameplay, but I didn't have enough context from the scene itself or anything before or after to understand what was really happening or what it meant.
The art is a bit of a mixed bag. The style stands out, and some of the backdrops are really nice, but it's hard to tell platforms from backgrounds in some sections, and the player sprite just looks odd. I'm not sure about the enemies either, which can only be described as vague-looking.
A lot of the music is really quiet, and some of the sound effects oddly chosen.
Platforming felt okay. Not amazing, but not bad either. I did feel the main character was a tad slow, and wasn't sure why my punches could hit enemies so far away. It's also possible to spam punches much faster than the animation can play. But the level design is generally pretty good, and there aren't any frustrating parts that wear out their welcome.
The shmup sections were pretty well implemented, with a transition that makes sense, but on my browser the up and down arrows scrolled the page which made playing them frustrating. I also realized pretty quickly I could just zip past the enemies. The boss shmup section was an interesting change in pace, though, and one of my favourite sections in the game.
I made it to the section with broken platforms and couldn't figure out where to go; everything seems to be a dead end. Because of how abstract this game is, I wasn't sure if that was deliberate or not.
I like what this game was trying to do. I think it has some solid ideas, and some of them did hit the mark. But overall it has that feeling of an ambitious, unique concept not quite realized to me.