This was a cool game! The graphics had a unique style to the that stood out... I especially liked the sketchy illustrations and the "other world" for the SHMUP sections.
This game begs to have some audio, but you did say that was in progress. The actual gameplay was decent, but didn't stand out too much. The platforming was solid, but could use some more fleshed out levels. The SHMUP was a little better, and gave me some really nintendo-era vibes. My only really issue there was that the player hitbox was a little weird. Felt like it might be a little off-center and to the bottom. I died countless times scraping my feet on walls, which did get frustrating.
The ending in the hospital was surprising and pretty memorable! I didn't realize there was another ending before reading a comment below. I went back and checked that one out afterwards. (The hospital ending is my fav though)
Overall this was a unique and interesting game. You called this a demo, so it'll be cool to see you expand it!