Good execution on a good concept. I ran into an issue where occasionally the R or F key would stop working and not let me toggle the rotation mode, not sure why, the only fix was to refresh the page (maybe something on my end, who knows).
Presentation is fantastic, however I at first got confused as to why the player couldn't move, which I had assumed to be a collision bug until I realised it's because the level is hitting the sides! When that realisation struck it made sense and I loved it.
From reading some of the other comments, it seems I'm not the only one regarding that. Maybe a simple shader that makes the side of the level that is hitting the edge glow or something? Explaining the mechanic is good, but it's best to show it because not everyone (like my lazy ass) will read it.
I didn't get to finish it, but the foundation is set for an amazing title. I wouldn't even be surprised if I saw this on steam for 15 moneys.