I feel like the game is a bit all over the place, which is kind of standing in its way.
First impression was I was completely lost and didn't really know what to do. I saw the controls, but they didn't really seem to do anything or weren't relevant in the beginning.
Next thing I knew, I was wondering around and the fireball now worked, so I just wandered around aimlessly killing slimes and at some point skeletons. The overall goal is stated in the beginning, but it doesn't really mean something to me as the player at that point or give me something to work towards. Places where I would transition between screens were not really clear as well, so in the beginning that felt like stumbling around.
The mechanic I really liked was "Shift Reality". The puzzles around this, for example in the tree stum maze, were really cool, and I felt clever solving them. I feel like maybe a level based approach around solving levels with this mechanic in the center might have been a better choice than what feels like an open world. But take that with a grain of salt, because I really like puzzle games. It's also that the Shift Reality part didn't feel like it was ingrained with the rest of the mechanics, so I feel like this mechanic could very much stand on its own.
If you want to keep things mostly as they are, I would say giving the player a clear direction and sense of progression would help. Like "ok, start by going to the wizard's tower to the east" or something along those lines. A clear visual language also helps to show the player what he can and can't do and what he is supposed to do. For example starting with a small tutorial area and then having a bridge away from it can help show the player that he's meant to leave that area and in which direction to progress.