So im sure at least some of you have heard of lasers and feelings by john harper games and one seven designs, an RPG game whose rules fit onto a single piece of paper, and player character sheets fit onto a notecard. If not, follow this link: http://www.onesevendesign.com/laserfeelings/

I love this system because it takes maybe 25 minutes to just start a game, less than 10 if everybody knows the idea of what they want to play this game.

Contrast this with call of cthulhu by chaosium, which uses robust mechanics to create greater mechanical depth but limiting creative options in several key ways to make somewhat specialized characters or generalist ones in order to create a diverse player character roster. CoC requires roughly 30 minutes to an hour to create new player characters and it requires allot more mental attentions, even before a back story is fully realized if your just planning on playing a pick up game and don't take the suggested route of writing a character story and then building off that. (A note here, i haven't had the opportunity to play or GM a game of call of cthulhu despite a deep yearning for it, and as such i may be inaccurate in my summarization)

So, when playing lasers and feelings i noticed a pivotal design in it that made me think it could be an excellent CoC lite version: lasers and feelings has no level progression system, which means it has no power creep; baseline humans are just humans, they don't get exceptionally stronger or new abilities, they just survive encounters. The power comes from the player retaining the lessons they might learn from a given interaction and applying sensible actions. Both are styles of play i wanted to reinforce.

Cue "Tomes & tentacles", my Call of Cthulhu hack of lasers and feelings. It adjusts character qualifiers (specifically the roles), swaps a ship for an investigation agency, and adds a sanity system and spell list. Magic is available to anybody but is almost always perilous. Each player starts with an eldritch scrap and anything their character would reasonably carry on their person, as well as a starting credit/money pool of anywhere between $200 to $500. The few games i've run of it have succeeded pretty well to terrify and intrigue the players in my group who stepped up to the plate of being a human way in over their head.

Tomes & Tentacles

You are a private eye/investigator touched by the paranormal, who is part of an agency which seems drawn to the darker world at large. Adventures into the paranormal await you as you brush shoulders with the mundane, the preternatural & the eldritch, often all at once. Insanity & mutilation an ever present threat, you struggle against the forces of darkness to find the truth and earn a paycheck.

1) Choose a style that determines the first half of what you're an expert in from; Hot-shot, Cautious, Insane, Sexy, Scholarly, Crafty, Tech Savvy, Cultured, Worldly, or Stoic

2) Choose a role, the other half of your expertise; Private Eye, Librarian, Politician, Doctor, Cultist, Mobster, Escort, Construction Worker, or Gambler

3)choose your number from 2 to 5. A lower number means you are better at Tentacles rolls (emotion, impulse, & intuition), and a higher number means you are better at tomes rolls (logic, reason, composure and technology)

4) Select one of the following for your character to begin play with; an eldritch scrap, a servitor entity (the exact nature of which you don't necessarily know), an illegal contact/associate, a lesser eldritch artifact, a suite of protective mystic tattoos, a large boost to starting funds (up to $3,000), extensive occult knowledge, or a high profile contact.

5) As a group, all players decide on the name and nature of your headquarters (typically a detective agency) as well as 2 strengths and 1weakness from the below lists
>Strengths; Sturdy build, spacious, well-stocked, medical facilities, CSI facilities, an old arcane library, backup generators and utilities, or secret rooms and tunnels
>Weaknesses; shabby, built on a leyline intersection, cramped, no storage, no utilities except electricity, cursed/haunted, condemned, on a Jehovah's witness Door-to-door route.

Your starting gear includes a standard vehicle, a civilian accessible firearm, and anything that could be justifiably be carried on your person. You may also state that you have some gear in your vehicle, but it can't look like you live in it (even if you do)

The rolls:
Any given roll is either looking for tomes or tentacles. A tomes roll wants to roll under your character's number, and a tentacles roll wants you to roll over your number. So for an example, if your character's number is 3, you want to roll a 4 or higher for a tentacles roll, and a 2 or lower for a tomes roll. If you roll your number exactly you gain an "eldritch insight", where you may ask the GM any question which they must answer truthfully, though they can be cryptic, and some questions can be refused if it gives too much away.

Spells: eldritch scraps and the necronomicon contain spells, powers beyond the scope of mortal forces. These spells are typically risky to players and can have more effects than what's initially stated. Make a list of spells that can be randomly chosen that have a chance to incur insanity points or cause bad situations for the characters, with a few "safe" spells thrown in.

Insanity: each rank of insanity is made of points, representing a measure of mental instability. They are gained from witnessing unnatural occurrences or scenes of extreme violence.

1 point is awarded by seeing mundane disturbing images like holocaust footage, violence, bad accidents, or other distressing material without warning or time to brace yourself. A single point represents little more than becoming disquieted

2 points are gained from more extreme imagery such as gruesome murder scenes, horrific diseases or animal cruelty taken to it's height.

3 points represents the extreme of mundane horror, often caused by snuff films, the direct experience of prolonged torture, and unethical scientific experiments going horribly wrong. This also can be gained by witnessing phantasmal creatures.

4 points is typical of witnessing things which should not be, such as shoggoths, old ones, and the usual minions of the elder gods. No mundane human experience can equate to this level of unhinging terror.

5 points is reserved for the higher tier mind-breaking sights, such as the sunken city of R'lyeh's non-euclidian geometry, undead re-animated by eldritch means or impossible sights. Insanity can be reduced by therapy, relaxation, and rest, taking a day for every point.

1 rank of insanity (10 points) is very hard to gain all at once, but witnessing an elder god in the flesh(?) Will do the trick if you're so inclined

Upon gaining 5 ranks of insanity your character becomes unplayable.
0 ranks = mentally stable
1 rank = mental disquiet
2 ranks = minor schizophrenic voices, paranoia and nightmares
3 ranks = sleep becomes near impossible and always filled with night terrors, you experience hallucinations, and have gone diagnosably insane
4 ranks = you dont sleep anymore until you hit complete physical exhaustion, the veil between reality and the other is sheer to you, and you can see the unseen monsters that lurk behind it.
5 ranks = unplayable, your character becomes a vacant vessel or inhabited by something... Other, conjured by the beacon of madness.