Ok I managed to figure out the problem! There's no marked door in the first room but if you randomly bump into all the walls you'll eventually find where it is. (Middle of bottom wall)
Then I played through all the fights and fed all the ingredients in the right order and.... got the same ending! I guess there's no option except "the demon destroys the world", lol? I feel that's a pretty creative interpretation of the theme! The wizard's problem is they refused to "just get started", they jumped into a really big ambitious project as their first idea instead of starting small. So they're always doomed to failure.
Still, I'd recommend adding the same shadow graphic to the first door that all of the others have. It'd be really helpful in making sure players can experience the full game. Gonna increase my rating now, yay! - Bonnford