Dedicated cover. Seems like a lot of people are doing that this year. Not a huge issue, especially here where the page size is A6 instead of A5. Not a lot of real estate lost in exchange for some concept gains. My only critique would be that the choice of cover art feels far more like an old video game cover than an old paperback. Not speaking ill of it, simply letting you know the first impression I get from the visual.
Back cover is loaded with vital information. Good place to put things you want to reference regularly. 2 NPCs of note, an encounter table, a note on how to stat the encounters instead of needing to explain them completely. Pages don't include numbers visually, but I would still reference the page number the chimeric mutations are found in the Hybrid note. Especially for the print version where the page number explains itself by flipping pages. Last is a list of Science Fantasy relics. The trope is certainly suited to the era of pulp fantasy novels one might find in the Appendix N. A good number of these aren't just benefit alone, which is good. Having some 'curse' there as well means things get more interesting and requires more thoughtful usage.
The situation is straight forward and well marked with bold call-outs. Overview of the setting is clear enough as well, though calling out 'clawing kudzu' had me immediately glance over to the mutated flora chart. If only the word 'kudzu' was bold, I wouldn't have looked over. Adding clawing made it feel like a monster call out rather than a visual highlight. It's nice to add more flavor again in the form of magic as psionics. It's reskining rather than trying to create an all new system.
Lots of hook options. I like this. Many products focus entirely on rumor tables (I'm guilty of this as well sometimes) as a means of getting people involved. I like that you have multiple directions to approach it based on the type of players you have. Motivations of wealth, prophetic visions, hope of useful information, etc. Not just “A thing is happening over there”. Good choice.
Under the Chimera entry, is it meant to be 'rarely'? As to the Chimeric Lord, I like that he's not some endlessly obvious evil to defeat. Kind, wanting people treated fairly, etc. On entering the next page, your entries immediately are referencing valuable information. Number of guards, page number to find the hook, which Roman numeral to move to for location data. Good. Excellent in fact. Highly valuable as a GM trying to pull this out of a folder after a long time not looking it over.
Okay, technically I get the map first, but it's serviceable. I can talk about that though I suppose. You've kept things from getting dull by the use of the kudzu images snaking around the borders of pages, so art isn't really lacking here. There's always something to keep a page from looking like a wall of black and white. Heck, you even use the kudzu leaf as a bullet, which is really smart. The map style is in keeping with the cover, so makes sense. What I don't like about the map is just a personal thing.
Every mountain has the exact same markings. Cut and pasted peaks regularly spaced around the valley. I get it. They're not really important to the situation and players probably aren't going to go exploring them. Still, for me, many entries only have that map as the core visual in the interior. If you do an expansion, it would be worth it to consider remaking the map with a little more time and care put into the seemingly-unimportant elements. Feeling like time was taken on those small details lends a sense of care to the design of the map. At the end of the day, all that matters is knowing what is where and I understand that. A hand sketch with circles and lines can do the job. Still, you clearly cared enough to make it more than that and I feel it's worth the little extra time to go all the way. Not a point issue, just a sentiment.
Back to the adventure. Lots here for hints of what is going on. Some set interactions where player actions matter. Waterfall though bothers me. The minute some players realize there's no down side, I have known them to go gung-ho on the option offered. I'd add some sort of risk of negative effects rather than always positive mutations.
VIII notes several vehicle objects not noted in the document. Given the system neutral element, just noting something suitable as a similar concept for scale would be nice. For example, the skimcycle could easily be noted as “Speed equal to a horse at full speed up to 6 hours. If allowed to cool 4 hours, can be used again. If run more than 6 hours or not allowed to fully cool, may overheat and explode as a fireball 2:6.”
Under IX, I would bold the whole stench of death element. So now on to the keep. Not going to lie, it feels very weird doing a random dice roll to decide how many rooms are in the keep that capstones the entire adventure. Only the 4 seem to matter though and I'd have to figure out where in the world they all fit together. If I am running this on the fly, I am throwing all of that out and just using those 4 rooms. Small keep. It is what it is. I read it over and then go to scroll to the next page to see what we have next... and there's nothing there. We reached the end.
Kudos on the game setup. I was all in. I was lost in what was happening enough that I wasn't keeping track of what page I had reached. But the ending feels abrupt and painful. I know I can make all of what happens from there up. I do it all the time. But when I am pulling out a premade adventure, I am doing it so I don't have to do all of that extra legwork. This is an amazing first half of a larger event. I say do expand this. Add a second half to the adventure where players are forced to make a hard choice between a kind man with cruel methods verses a status quo being restored even if it isn't pleasant. No obvious good or evil, just two people with their own goals using what tools they have access to. Hard choices. These were my final thoughts as I got to the end.