Cover: The layout and typography is pure Appendix N. I like the image of the throne and the way the same colour palette is used for the background.
But who is the guy on the throne? It looks like he wandered in off the set of Trainspotting. Is that a joint between his fingers? Is this fantasy or social realism?
Interior layout: Overall fonts, colours, layout work quite well, it definitely has a zine vibe to it. White text on blue background is very easy to read, but black text is not high-contrast enough.
Map: very clear and I love the hand-drawn illustrations. Again it says zine to me. I did the same thing as you, putting the map and location descriptions on the double-page interior spread and detailed stat blocks on the back page.
Editing: some of the text would benefit from reordering/reorganisation. e.g. “Roots” describes legs sticking out, then the plant, then “his head and hand have been dissolved”. The spectacles in room 4 should be mentioned in the description for room 1. “Throne Room” describes Cadwin, then frog-people, then Cadwin again. There are a few typos (spelling/punctuation).
Adventure: It’s a classic setup, a quest to learn the fate of the king’s sons.
You succeed in creating a whimsical ambience which I imagine would be a lot of fun to play. Some of the encounters combine whimsy with deadliness, which means that it’s not too predictable. The party are kept a little off-balance and have to have their wits about them.
I love the pamphlet with tips for self-esteem.
Overall, this looks like a quirky and fun one-shot adventure. Nice work!