Editing Call of Cthulhu (section)

==System==
''Call of Cthulhu'' uses the [[Basic Roleplaying System]] (BRP), first used in ''[[Runequest]]'' and also for ''[[Stormbringer]]'', ''[[Elfquest]]'', and a variety of other games. It uses an array of D&D-style attributes (STR, DEX, INT, CON, POW, EDU, APP, SIZ) rated on the familiar 3-18 scale (since 7ed those are on %-scale), plus around 60 skills rated as percentiles.

===Basics===
To perform any action, roll [[d100]] and try to get under your skill; rolling 1/5 of your skill is a critical success, or an 'impale' on an attack. Used skills are marked and at the end of the adventure may increase by 1-3 points if you succeed in rolling under the inverse of the skill. This leads to very gradual and organic character progression, and encourages players to use as many of their skills as possible at least once per adventure. Attributes are checked in exactly the same way, though are typically multiplied to make the check passable, typically by 5. Another option is comparing them to an opposing score on a resistance table, for every point of difference the check is 5 points easier or harder, and 10 points difference is either an automatic success or failure (for example, someone with 10 STR trying to bust a door in with 12 STR has a 40% chance of doing so). Damage is handled via hit points, which for PCs never advance beyond the region of 10-20, though if they can justify it to the keeper they can get armor.

===Character Generation===
Chargen is a relatively long process due to the number of skills and the percentile values, although the free program [http://sourceforge.net/projects/byakhee/ Byakhee] is available to speed things up. You roll attributes, select a profession, gain a bunch of skill points to spend on your professional skills, (such as archeology or painting) then a bunch more to spend on your hobbies. For instance, firing Tommy-guns (which definitely ISN'T a total waste of points).

===Gameplay===
Investigators are typically unable to go toe-to-toe with the monsters in CoC, so most of the game consists of investigation, exploration and gathering clues, with the investigators typically finding something they can do to either destroy or banish the thing that has been ravaging the area. Imagine Scooby-Doo, except with eldritch, inter-dimensional horrors that will almost certainly kill you or drive you mad (so basically imagine the Scooby-Doo Mystery Incorporated finale), and who are impervious to most weapons humans can muster outside of a goddamn Howitzer (or a passenger ship, or everyone with a boomerang) to deal with (though, shotguns ''should'' work for anything roughly man-shaped), rather than Old Man Withers dressed up as a ghost to scare away the locals.

If you are lucky your investigations will allow you to reach any sort of confrontation armed with magic (which, you guessed it, drives you insane to use), a list of the creature's weaknesses, or at least a metric fuckton of dynamite. Spot Hidden and Library Use are two of the most commonly used skills and any player that thinks a gun is useful for anything other than intimidation will be having a fun time swimming inside a Shoggoth or using it on themselves to stop the voices.

One thing of note is the difference between pulp and purist play, each one supported by different rulesets as of 7th Edition. Purist is ''Call of Cthulhu'' "as God intended"; where investigative mystery comes first, witnesses and research are your main weapons and the real thrill comes from the intrigue and the sheer threat. Pulp is ''Call of Cthulhu'' as the Lovecraft-Lite action-adventure game, where the Mythos ''can'' be pushed back with judicious use of firepower and dynamite and humanity ''can'' prevail against the encroaching dark... at least for a time. Pulp stories tend to be more internationalist as opposed to being in one geographic location primarily, and the timeline is brought forward a bit to the Dirty Thirties - the Great Depression is in full swing, liberal democracy is under threat from a sweeping tide of authoritarianism, most Americans are dirt poor and/or unemployed, quick and cheap intercontinental air travel is now a thing, and movies no longer suck. Characters in pulp games have more HP and become quite a bit more likely to survive, but it arguably loses some of the horror and imminent danger that comes from purist play. There are merits to both styles so give 'em both a try!

===[[Sanity]]===
Sanity or SAN represents your mental stability. It is capped at the inverse of your Cthulhu Mythos skill; that is to say, you ''cannot'' know what is really going on and remain sane. When you experience something terrifying you make a SAN check; if you fail you lose a random amount of SAN, and often a small amount if you succeed as well. If you lose a substantial amount (five or more in one go) you can have a panic attack, flee or any other sort of madness, though you have to roll to repress the memory of the thing you see first. If you lose a very large amount (one fifth in a game hour) you can develop phobias, mental conditions, or go insane for months on end. If you run out entirely you become an NPC, who may go insane and gibber in a corner for the rest of his life, or he may go and join the bad guys. It's not all bad though, as going insane from something mythos-related actually gives you insight into the thing you have seen.

Sanity loss is a source of both frustration and good roleplaying opportunities, as on the one hand playing out multiple personality disorder can be good fun. On the other hand being trapped in a hole with a monster is bad when one character has a darkness phobia and is curled up in the fetal position, one is claustrophobic and has fainted and one with a snake phobia who refuses to use the rope to climb out can be either [[Butthurt|frustrating]] or [[TPK|Fun]] for player and keeper alike.

SAN is arguably ''the'' contribution to RPG settings at large - in reverse. We will find Taint in [[Avadnu]] and Insanity in [[Tanares]].