The Mythos Files: A Cthulhu/X-Files Mashup


Atlantean Sorcerer
Validated User
Hi All,

First post for me in a while...I'd been in gaming hibrenation, but it's Spring again...

I've had this on my back burner for a while, a Mashup of the Cthulhu Mythos and the X-files. And while I'm waiting for my D&D gaming group to be available to play again in a couple of weeks, I thought I'd move it to the front burner, throw some dough against the wall, and see what stuck.

One can see how the two series would mesh well together, both center around investigation of the truly unknown and terrible (whether that be the Old Ones or the Aliens of Area 51.

Just let all that goodness soak in and get your creative juices floating on that...

A few questions for input (or at least thought by me if no one else is interested):

1) What rule set - The no-brainer is to use the Call of Cthulhu rules and update them for more futuristic things (like cell phones - whether they be the 90s monstrosities from the original series or more modern phones, gps, etc.) or something else altogether (FATE, d20, GURPS) OR even a completely homebrewed (or Frankensteined) ruleset (I dabble in these a lot). What are your thoughts?

2) Nature of the Cthulhu Mythos *actual* involvement - Is it direct and apocolyptic OR (as I'm leaning towards) very subtle and mostly an influencer of the Cthulhu cult (with an occasional off-camera intervention...perhaps with that crucial witness npc)?

3) OK, so we have the Old Ones, Cultists, FBI Agents (and other competing adventurers)? What else? Do we keep things like the Men-In-Black? What else? What would you like to see in there?

4) Other thoughts?

I'm going to keep building on this, both at and on my blog at High Adventure Games. Your thoughts would be most welcome!

Game On,



Atlantean Sorcerer
Validated User
Very cool! Thanks! While I'd heard of the title before, I had no idea that Delta Green included that stuff.

Very Best,



This Space for Rent
Validated User
If you want the whole enchilada, you should look up everything Delta Green related. The original stuff is listed under Pagan Publishing while the recent stuff, like the one I linked to is from Arc Dream Publishing.

All of it is good.


Validated User
I think that the Cthulhu Mythos plus X Files is pretty close to the core trend of Chill. I've got a copy of 3e that I've been wanting to try out, so there's a pretty good chance that I'd use it if I were taking on this concept. Having the PCs as in the know law enforcement should work out well enough. It'd turn out closer to the X Files if they were a bit independent of SAVE (the big secret monster hunting organization), but I could see it going either way. The system might be a little bit deadly for the X Files, but it does fit that whole constant threat of death and madness thing that the Mythos has going, so that's fun as well.

If I wanted to go way more over the top, I'd be tempted to use Atomic Robo RPG, which runs on Fate Core. There's way more potential for borderline super heroics and over the top mad science. Which I'm always tempted to include. I'm also super fond of the brainstorming mechanism, because it's very helpful for when I feel like being a lazy GM. Which is always.


Registered User
Validated User
In addition to Delta Green (which all but defines X-Files and Cthulhu mash ups for me), I think The Esoterrorists could be a good setting/system to use. Another game that may interest you is Silent Legions.
Last edited:


The Truth is Out There
Validated User
Very cool idea! You had me at X-Files. :cool: Delta Green does indeed sound like the perfect game for what you're doing. Folks here steered me towards it when I was doing my own X-Files game.

Cloud Divider

Registered User
Validated User
There's also the Laundry Files, but that's a whole ocean away from the X-Files ;)
Heh. I see what you did there. That said, this side of the pond does have The Black Chamber, so there's that.

The Laundry Files (novels and RPG) are a fun (slightly) alternative take on the genre. Certainly worth a read, if you're a fan. Maybe Delta Green by way of The Office, I guess. Being not quite as deadly serious as DG or Esoterrorists is something that works in its favor, I think.

That said, Delta Green is certainly where I'd go first if I were looking for X-Files meets Mythos. It all but says it on the tin. Also has some pretty good modern mythos books published under the line. There are also some really excellent Actual Play writeups over in the Actual Play forums that are worth the time.

Esoterrorists is worth a look, if only for a worked example of the GUMSHOE games system as applied to the investigative horror genre. One of the biggest problems with any kind of extended investigative campaign, is that it's all too easy for the players to get stuck (they couldn't find the clue, or more importantly, couldn't *interpret* the clue properly), or distracted (red herrings or racing down the wrong rabbit hole). It's a failure mode that's substantially different than the usual things that go wrong in other games/genres. The commentary in Esoterrorists isn't entirely tied into the rules, so it's something that can be easily exported.

Not sure if OP is looking for possible game systems, but a bunch of options have been mentioned (Call of Cthulhu modern, Delta Green, etc).

One that hasn't yet (might be out of print) is Conspiracy X. I once (ages ago) played in a ConX campaign, which had a gimmick somewhat similar to X-Files and Delta Green, where the agents all came from different backgrounds, but were brought together to deal with something bigger. One player was FBI, another was CDC. My guy was former Yakuza hitman, sidechanneled into a secret experimental program where he was brainwashed into the conspiracy. He was given his orders via the monthly Video Game Magazine's CD of demos... (this was back in the days when Playstation Magazine shipped with a demo disc). It was kinda silly, but fun, too.

The campaign itself ran aground on the Investigative Game problems mentioned above (players got sidetracked, started spinning wheels, GM didn't want to force us back onto the trail), and it ended up dying out from the perceived pacing problem (players weren't getting anywhere, because we were looking in the wrong place).


Registered User
Validated User
I would suggest such a thing start out subtle and gradually escalate. At first, you encounter things like someone stealing all the bodies in the morgue and eating them (they have read a tome which filled them with a lust for flesh, and eventually they will mutate into a ghoul if not killed first), a terrorist who blows up a church ranting about fish people (he thinks they are deep ones, but actually, he has just enough tainted DO blood to have visions about it which have broken him), a mathematician trying to solve Fermat's Lost Theorem, who announces he has found the solution and vanishes (he's invented a gate and landed on Yuggoth and now the Mi-Go have him), a man who ranted about lizard people tried to shoot the mayor, failed, but then was murdered by a cop in the jail, who then died in a car accident (a panicky serpent man hiding in the town is behind it). And so on. Interspersed are cases which are weird but mundane.

Then you gradually escalate to where the PCs are dealing with cultists and sorcerors with real power and finally some kind of giant occult/outer-space conspiracy.
Top Bottom