I played the game! First of all, the universe-changing mechanic was quite interesting at the beginning, but after a while I felt that it started becoming repetitive and the possibilities of what could be done with the mechanic felt a bit limited.
For a game like this, trying an open-world approach was a really nice idea. However, after progressing for a while, I got a bit lost and had trouble understanding where I should go next. If the world gets filled with more content and points of interest, I think this system could offer many more interesting experiences.
On the audio side, there was one sound effect that I couldn't really understand when it was triggered and it became a bit tiring to listen to. I think it might be the looping SFX that plays for a while after picking up the key. Other than that, I think the overall music and sound effects were quite good.
Visually, the game looks great. The drawings and overall atmosphere are really nice. However, I felt that the feedback when interacting with things was a bit lacking. For example, instead of a direct transition when changing universes, a smoother transition with additional character movement effects, particles, or other visual feedback could make the experience feel much more polished.
I haven't played many games in this genre, so unfortunately my feedback might be a bit general :D But overall, I think there are some really interesting ideas here. Good luck with the development!