Found a pretty annoying bug: You can fall outside of map (at least in door 1) and there's no restart level key. So you have to reload page and lose all progress :(
Repro: I was climbing the right hand side ladder and got out of bounds GIF
Fixed this in the new version, once you go out of bounds you'll return to the starting position. You can now also press ESC at any point to return to the main hub.