I have planned my next FARP (stands for Forum Action Role-Play) for ages. I started planning it last year, but still haven't started it. I have to thank future players of that FARP for their patience.
First I planned to use my own rules set for the game, but decided to ditch it. My own rules are just at way too early stage to work properly. Actually I thought that FARP might be ok to playtest it, but there is still too much work before actually playtesting the rules. So, I had to make a decision to use ready existing set for the FARP.
I have been playing Call of Cthulhu at home for 2 or so weeks and nearly 20 sessions for now, so I decided to use CoC BRP system for the FARP also. Call of Cthulhu is also familiar game for the players I would be game mastering. I can use rules and dice rolling in FARP as they are presented in rules for I trust my two players that they wont cheat. BRP is good for FARP, because the rules are really light and easy. Not much rules twisting, everything works almost with the same mechanics. And as my game is horror with normal people, insanity rules are absolutely a must.
But, as CoC is behind it's surface about Mythos, and I am not using Mythos as the background of my horror scenario, I wanted something else to fill that empty slot. Kult RPG.
Kult is the game I love the setting really much. It is totally awesome, gives dozens of adventure and campaign ideas just by reading it and it's universe is actually quite horrific.
So, BRP as the rules set and Kult as the background setting. I also like Mental Balance rules in Kult. When you see too much stuff, you see through Illusion and horrible things happen. I decided to include that in BRP rules and with just a little thinking it is quite easy. Replace Sanity Points with Mental Balance and 99-Cthulhu Mythos with 99-Terror. You can ditch the skill Cthulhu Mythos as it is not needed.
New characteristics Mental Balance and 99-Terror work as their original source. There is small houseruling though:
- When character encounters something horrible, make SAN check based on current Mental Balance. If your score is lower, you success and loose minimum amount of MB (Mental Balance). If you score higher, you fail and loose maximum amount of MB. Amounts of MB are concidered as in Call of Cthulhu (ie. 0/1D3).
If you loose 5 or more MB from one encounter, you gain temporary insanity (as in CoC rules). Throw a table how long it lasts. After it, throw again against your MB score. If you roll higher, Illusion shatters and you see through it (as long as your temporary insanity lasts). See more information about seeing through the Illusion in Kult rulebook.
When trying to resist the truth behind the Illusion, use character's Idea.
Notice, when you encounter scary and horrible things, you're 99-Terror value decreases. It indicates your maximum possible Mental Balance. More you loose MB more easily you go nuts... and see through the Illusion.
More about setting and rules check on Call of Cthulhu core rulebook and Kult RPG core rulebook. Everything is detailed there. This is just a fast conversation to use Mental Balance rules of Kult in Call of Cthulhu.
In my convertion I have referred to Call of Cthulhu 5th edition and Kult RPG 1st edition. Rules between different editions may differ.