This was a fun one! I love a good survival horror and the environmental hazard is unique and fun, it fits well in the pulpy sci-fi horror space too! The layout and general presentation are pretty clean. The font size is small, but about what I'd expect for a (presumably) US Letter sized trifold leaflet, and is readable for me at least.
The Map is solid and well labelled, my only real qualm is that the first three icons in the legend are slightly too similar at a glance: I understand the intention and the logic behind them, but at the scale of the map as given, they are slightly hard to read without zooming in or peering closely, some higher contrast icons would probably be easier to pick out and identify, but actually having icons is a good touch and works well!
I think some less verbose room keys would allow you to separate them a bit and give the interior pages a bit more breathing room. currently despite being separated by text frames they still feel slightly cramped. I think just some minor edits would make this easier to parse, but as is it is still great!
This one is highly polished and compelling, I'll definitely be running this one!