You did a fantastic job on the atmoshpere.
I felt really happy being inside playing this game.
I think this is a really great game, but it doesn't come throuhg because of some small things that cause great frustration. Even though I couldn't help but quit at chapter 4. Because of some small issues that are really easy to fix but caused me too great frustration sorry.
Improvements.
1. I died and then I had to start all over again this really frustrated me. I would have loved checkpoints.
The game would be way less frustrating for me if you added more checkpoints. A nice place to add these checkpoints
could be at each new mechanic introduction. Like after you learn you can use Ko as a little umbrella,
or after you get introduced to the oscillation device (google wip+ speeltuin).
Would you be interested in doing a game jam together? We can learn a lot from eachother. I could help with design and programming.
You can check out my work here and see if you're interested.
https://jaswir.newgrounds.com/ (Pirate and Tough Growth my best)