I'm glad you enjoyed it! I GM for a group who always join any rebel/underdog group at the soonest opportunity and the ICM as a whole are definitely the type of faction I envisioned for those types of players.
The idea for this pamphlet basically came from a mini-setting idea I've been kicking around for a year or so, nothing particularly detailed yet but I might work on more in the future. I wanted it to be a very cramped, claustrophobic setting that lends itself well to the kind of dungeon crawling game-play I usually incorporate into my games. Metro tunnels and sewer systems felt like a good way to encourage that without it feeling terribly out of place in a sci-fi game. The overall focus would be on the factional conflict going on, even from within the groups who make up the ICM, but I want to leave a lot of room for pockets of bizarre alien life or occult shenanigan to reinforce the horror vibes. I think a sandbox setting where half of the challenge comes from navigating these open war-zones controlled by groups with different allegiances would be interesting. Let the player crew decide how they want to influence it and who they want to throw their lot in with.