How does one get through the door?
Touch the door and you change the level.
Are you having a bug in the beginning? I played through this twice without the bug, came back a few hours later to play again and encountered a bug where I can't see or move the player at the start.
Thanks for the warning. I uploaded a new version. If the bug continues, write a comment.
I've been having this issue with a lot of games in the browser. Refreshing seems to solve it for me usually, but not always.
