"THANKS FOR PLAYING! To play the secret (and stupid) Debug world, start a new game and hold the MENU button under the dark red sky while walking around. You will be transported someplace different..."
Is what the game says. The Menu button is the X key. So just hold X while running from the demons on the second screen and you'll be teleported someplace different. And horrible. I barely knew how to program most of that.
Thanks for playing! I'm assuming this means you beat it, hehe. I'm well into programming the next world now. There may be an update soon.