DEMON CORE is a mission for FIST.
The PDF is 32 pages, with good maps, graphical noise, photobashed illustrations, and a generally clean and highly readable layout.
Contents-wise, the mission here has a strong 80s action movie vibe, perfect for FIST. CYCLOPS is in possession of an evil nuke and is planning to disrupt a global summit, and it's your job to stop them.
Challenge-wise, this is a fairly different mission if the players follow it to the letter versus if they get curious. By-the-books, the opposition is numerous but mostly mundane, and everything can be handled with a bit of gunfire and decision making. Get curious, and things get nihilistic fast.
Included in this mission is a big pool of tactically interesting CYCLOPS agents, which can be fielded in this or other missions.
Overall, this is a solid, fairly purist FIST mission that could also work for systems like Delta Green. It's well-researched, structured, and written, and should pose a solid challenge and/or wipe out curious PCs.
Minor Issues:
-To me, it's a little strange to me that CYCLOPS is trying to do a terrorism here. It's definitely not totally out of character, since their objectives are generally murky, but it feels a little weird for the agency in the stronger position to be wildly stirring the pot like that.