The idea is great, having switchable dimensions and some form of combat / gameplay linked to it would have been great to see, but we all understand that we can't fit it all in during a jam.
Some points though, if you are running WEBGL builds, do not put a Options / pause menu on the ESC button as it will exit fullscreen mode.
Also the menus seems to be broken.
Otherwise, sweet concept, would love to see it more expanded on.