Nice cover art and map! I like the fun little references like "cele-steel" rope. Very 8-bit vibe with the instruction booklet layout. You did a nice job combining the 3 games!

Lots to love in this! I would run it. Great job on your first release!

Usability:

• Overall this is a great springboard for an adventure, though I can see the GM needing to do a fair bit of fleshing out in certain areas if the players decide to really dig into it.
• For instance, in the Dorani Town I can imagine players trying to steal/heist the cosmic sphere instead of risking the Steelblade Cup. As the adventure is now, this would require the GM to completely synthesize that material. Also having some detail around the beastforged encampment sieging the town would allow players to raid/disrupt it.
• Similarly the beastforged outcast hideout could benefit greatly from becoming a keyed location. This would also let you increase the amount of treasure, which is something you noted as being on the scarce side.
• The adventure seems bottlenecked by requiring flight to reach the head in the sky. It would be good to add more than one solution to ensure there isn't a dead-end.
• Illustrations of the monsters would be helpful, particularly the custodians, which I had a hard time visualising.
• Wilderness map is a little hard to use; what is adjacent? Maybe break it down into a grid? 

Formatting:

• You've achieve a lot of good things vibe-rise with the formatting, but it comes at the expense of usability. The 8-bit landscape background is a bit distracting from reading the text in certain areas, and could benefit from being toned down significantly in contrast.
• The magenta header colour is a little fuzzy. Toning down the saturation would help.
• The bestiary layout is a little confusing with the beastforged stats being broken away from the core description.
• In general the layout gets a little loosey-goosey to fit things in, I think if you broke away from the NES manual page size, or increased the page count and introduced more structure to the formatting it would be a good thing.

Inspiration/Vibes:

• Great work! It feels not only in line with the material, but has a very 80s vibe in general.
• The steelblade minigame is a cool unique challenge.

I appreciated this supplement.  Vibe and inspiration are clear and well-thought-out. Arts really brings you in and shows the clear direction where this module is going.

As for usability, I feel key components are missing, even when excluded by choice (e.g., DCs, recommended party level, etc.). I also feel the density of text, coupled with the smaller font size and color scheme, makes it harder on the eyes than it should be. I also have to add that if I were to print this supplement, I wouldn't know how to fold it to create a booklet following the format it was created for, particularly for pages 7 to 16.

Still, a good entry that shows skills, imagination, and creative direction.

Very clear how the game inspirations appear in the final work. Very dense narrative and story components, does feel somewhat hard to plug into an ongoing campagin, but would work very well if pre-planned as a milestone area for  a new campaign. Missing technical work for DCs and encounters (intentional) which feels like more work for the GMs to have to handle in the moment. 

Steelblade cup is an interesting "mini-game" or puzzle mid-session that would be a focus of either one session or at least 1 full session on it's own.

Feels like a full world to explore rather than a single session or milestone for a group of players which is exactly what some GMs would be looking for.

Great job overall, good luck!