Operation Last Day is a Mesopotamian themed scenario for FIST that leans into the game's capacity for action-horror. You could probably also run this in Delta Green with no alterations---it fits that vibe perfectly.
The PDF is 16 pages, with a clean, readable, zine-y style layout.
Contents-wise, the writing and design is strong and interesting, but a little skeletal. Concepts are covered quickly, and the GM is left to fill in the details---but those concepts are fantastic and it's very easy to spin things from a hectic oneshot into a slow burn mini-campaign.
There's a lot of custom monsters included, all very flavorful. A particular standout are the multiple bosses, all with strong and consistent themeing.
There are also new Talents, and they're probably some of my favorites across all third party FIST material. The uniting theme is death, and they play with it in very dynamic ways.
Overall, this is a great scenario, well worth adding to your library if you even slightly enjoy espionage horror. You do have to do a little work to fill in the gaps, and you may want to generate some townsfolk in advance if you expect you'll be exploring the adventure from a slower and more political angle, but these are an easy admission price to pay for a standout.
Minor Issues:
-Page 7, "FISTenters" missing a space