All right, the first thing I noticed was your background and the color that you used. The main problem is the white dot on your background and the high contrast between them. When you start to move the player, somewhat, my eyes just can't stand it. You need to make it subtle in contrast between the player, background, and white dot.
I finally understand that dimension switching makes it possible for the player to reach the goal in another dimension. It's a good mechanic. But, idk, sometimes the player goes back to the start position after switching, and I misused it when I failed on parkour xD.
As others have already mentioned, the music and SFX are good choices.