Fell out of the level and couldn’t restart first. Second try, I escaped, although not sure what I did to do so, but the visual effect and the music was pretty cool!
Just adding a different color to the ground/ceiling could easily improve the maze’s look I think.
In our first person game I lock the cursor on every click which helps a bit with the browser unlock, fullscreen etc issue. I also found this repo by Jan since we’ve submitted that looks like a neat solution to deal with cursor (un)locking on the web, might be useful for you as well.