Project Nemesis is a fan driven website for games that use the One-Roll Engine (like Nemesis, Wild Talents, Reign and Monsters) or Chaosium's Basic Roleplay System (BRP) (like Call of Cthulhu) and the Delta Green setting.
I started Refing (Keeping?) CoC the year it came out - and went to a convention about six months after the game came out...
When talking to other players at the con - the common thread was "Cthulhu? Euuuuh! That's thegame where everyone dies or goes insane - where's the fun in that?" It got my hackles up a bit - and I decided that I needed to run a CoC game that went beyond that impression.
I knew that I wanted to run a game that was a long term campaign, that had continuity, aeons-long back history (true to Lovecraft!), and allowed players a little more survival rate s0 that it wouldn't violate one of my first rules of running the (any) game -- which is:
"It's better to let the characters live than die . . . once they die, they can't suffer anymore."
At that time I also had group of experienced gamers, (Straight up old hack-n-slashers) but utter newbies to role-playing, and wanted to include a system that would insidiously educate them into becoming excellent role-players through a hidden but pervasive reward system.
I also knew that despite the Lovecraftian viewpoint, I wanted the campaign to have a thread of hope in it. I figured I could crush the characters nine ways to Sunday, easily enough -- but the players wouldn't be coming back to the game, if they didn't at least *think* on some level that they had a chance of winning through. Besides . . . it's so much more satisfying to have the characters (AND more importantly the players) utterly emotionally involved - and then yank the chain for the big flush. You can't do that if they don't invest in the game on a lot of levels. (Someday much more on my theories and techniques for running the game!)
Early on - it became clear to me, that there needed to be an opportunity for the game to have an underlying philosphy that was in opposition to the Lovecraftian ideal. So that the players/characters would have the capability of not only just fighting the "Evil Black Things From Beyond Space And Time" - but the isolation, loneliness, division and soul blackening corruption that they bring with them.
The third piece is that I wanted to incorporate as much "real-world" magical laws as possible, but having a fundemental reason for why the folk lore says it works. i.e. - everyone knows that silver and cold iron is harmful to various magical creatures -- why? What is a ghost exactly? How does telepathy work? Why do some people have good luck and others bad luck?
Now - mind you - the ideas and the system have evolved over time into what it is today. I don't think about world-building as an intellectual exercise, and sit down and write up the laws of the universe before game play.
The system developed through many years of game play, and my own sense of "what's right" for the game in a dramatic and thematic sense, and the reaction and interaction of the various characters over the years.
Eventually - I met and marrried Chaz - who is a wonder at extrapolation, and we were able together to finally set down the laws of the universe into a body of die rolls, stats and rules.
But - the important part is that 75% of it is still hidden from both the players and the characters. They learn about how the rules work through their experiences in the game - not by handing them the print-outs and saying - "Ok - you know these three spells, and you can hop on one foot to make rain."
Whew! Having said all of that - we can start with
BASICS 101
We have in our game several different types of magic-users (I refuse to say classes!)
1. Traditional Lovecraftian Cultie/Sorcerers - those folks who want to open the Gates, Raise R'yleh, gain personal power, etc. etc. etc. (you know the drill.)
2. Traditional Lovecraftian Sorcerer/Researchers - those folks like Prof. Armitage - who are occultists, spell casters, but not involved in the worship activities. They may or may not combat such cults - but mostly they are the ones who are following the path of learning weird stuff for the sake of learning weird stuff.
3. Folk Magic/Religion - I lump into this things like Native American Shamans/religions, mid-wives, gypsy fortune tellers, Voudon, etc. These are folks who have demonstrated abilities that are tied to the practice of non-Lovecraftian rituals, religion or learned knowledge. Any of these at any time can be turned into an opportunity for a Lovecraftian cult - but most are just out there being what they are. This group would also include faith healers, or those who (believe) they work the will of God through themselves.
4. The Scientists - these are the alchemists, and materials workers. In the game there are certain "laws" of magic. One being that silver conducts, iron dispels. Given the belief and finding the evidence that magic exists and works - an engineer, chemist or just generally smart character can figure out all sorts of cool tricks to do with materials and magic.
5. The Gifted - these are your telepaths, clairvoyants, mediums, etc. Those folks who are born with or develop any of the traditional "ESP" skills. These folks are fairly rare in the game actually - since they are the result of a physical configuration deep inside the brain, rather than a learned skill. As all the stories go - they generally get smacked with their awakening abilities around adolescence.
6. The "Holy Knights" - this is a group of folks who really need an entire email all to their own - since they are the most complex and central to the campaign's philosphical core. Sometimes called "The Blessed" or "The Avowed" - think of them as people who have undergone a complex change through an oath-ritual that literally remakes them both physically and magically. They become tied into the magical structure of the World (the Divine?).
It has been quite interesting over the years to hear the discussion (heated shouting matches at times) as to if these Avowed are actually still human or not - given the changes that they have undergone. Are they people - or merely some sort of Servitor in human clothing?
Oh - another choice I made early on - was that the number 3 has massive import in the game. Since day one I've used it or multiples of it to indicate a point of Fate - or other motivating factors in the world. From the 3-days dead and then rise biz for vampires, to 3 opposing forces/factions in the world, to 3 forms of dreamwalking . . . etc, etc, etc.
Like anything repeated over and over, its become a running joke - but whenever the players make the connection between events and the number 3 - they totally freak out - digging for deeper meanings, researching, argueing - regardless whether it's true - or just a red herring.