Arkham Stories (I.e. the Cthulhu-hack I use)

 Those are the rules I use for my Chtulhu-esque investigation games. I like BitD, so it's inspired by that system. 

Rules:

Action roll: 

When the Investigators do a task to get what they want, and there is an interesting obstacle between them and what they want, they roll a number of d6 equal to the rating of the Action they use to overcome the obstacle. Those are called Actions-rolls. Actions can be suggested by the player, or they could be demanded by the GM. (Especially Endure and Focus are Actions that are often demanded by the GM, given those are more reactive than the others.)

What constitutes an "interesting obstacle" is up to the evaluation of the GM. However, in many cases, it's best to use obstacles sparingly. Not every task and question requires a roll. Just the fact that the players thought of asking and trying something can be enough to give the Investigators something in return. 

For every Action-roll, we look for the highest number rolled. If the highest die of the roll shows a 3, the Investigator fails - they should be ready for the worst (in RPG-speak: 'the GM gets to make a move'). Something goes wrong in some way or another, and the GM can introduce a new complication, AND the obstacle isn't overcome. If the highest die shows a 4 or 5, the Investigator overcomes, or makes progress in overcoming the obstacle; however, they might have to pay a price to do so(in RPG-speak: 'the GM gets to make a move' also). If the highest die shows a 6, they succeed without repercussions. If the dice show more than one 6, they critically succeed and get +1 Effect. The idea is that the GM never rolls any dice but simply moves when the narration demands, when the Investigators ignore an obvious danger, or when an Investigator doesn't get a 6 on an Action-roll.

The Investigators:

• Take 1d6 per rating of the Action they are using.
• Take +1d6 or +1 Effect if they get any help at all. Everyone helping is in the line of fire for consequences.
• Take +1d6 or +1 Effect per significant advantage ( great tools, great plan, etc. )
• Push-Yourself: Investigators can choose to push themselves. To do so, after any Action-roll but only once per roll, they can reduce their current Body for physical tasks or Mind for non-physical tasks (see that section) by 1 and reroll any of the dice.

If the Investigator has 0 dice left after accumulating a dice pool, they roll 2d6 but pick the worst of the two to evaluate the roll.

Aside from the potential dangers involved with acting on the word, another factor is how effective the Action is in overcoming an obstacle. That's where 'Effect' comes in. Every Action has an Effect of 1 and is modified by the schema above and by Perks. Actions that are very unlikely to succeed, either because of narrative disadvantages or because a task was chosen unwisely, can have -Effect. This means that the Investigators will have to make do with less than what they need to overcome an obstacle fully.

The way to think about Effect and more complicated obstacles is to treat them as extended tests on which Effect accumulates until the obstacle is overcome. Nowadays, extended tests are called 'Clocks', the syntax being that a 6-Clock requires a total Effect of 6 from different Actions to overcome. For instance, if escaping the cultists is a 6-Clock, Actions with a total Effect of 6 must be accrued to escape them. For more complicated obstacles, writing the Clocks down is helpful, though just keeping Clocks in the back of the head for smaller situations is enough.

As a general rule of thumb: Whenever an Investigator gets more Effect than they need, they should get some extra benefit for every point of Effect. That means, if they got +Effect and it's just a regular roll where we don't need Clocks, they can ask for extra for these rolls.

Body & Mind:

Whenever an Investigator suffers mental or physical harm, they roll a number of d6 = to their Mind or Body rating, depending on the nature of the suffering. They reduce the number of dice by the Effect of the threat: -1 if the suffering is particularly severe, -2 if it is life-threatening, and by -3 if it is caused by the mythos. The dice system for Body or Mind rolls works like the-price-is-right; when suffering harm, an Investigator rolls a number of d6 and attempts to get as close as possible to their rating in Body or Mind, respectively. After the roll, the Investigators then reduce their Body or Mind by a number equal to the difference between their current stat (NOT the number of dice rolled) and the closest number rolled. Armor or cover gives extra dice on Body rolls.

As rolling Mind or Body alone is equivalent to getting hurt, Investigators should only roll Mind or Body if they either ignored some obvious obstacle or as a consequence for an Action-roll.

If, after a Mind- or Body-roll, the rating of that Stat is 0, the Investigator suffers Trauma. The following things happen upon suffering Trauma:

• The Investigator is removed from the investigation. If the investigation still goes on for a while, the player will have to roll up a new Investigator.
• The Investigator loses 2d6 rating of their Bonds (See Bonds). If the rating of the Bonds is too low to lose the required rating, the Investigator becomes unplayable; either dead or driven mad.

An example: Alex gets shot by a small gun. They try to dodge but fail. Alex's Body rating is currently 2 because they were already injured. It's a gun, so Alex is told to reduce their pool by 1; 1 die is left. Their die shows: 4. A bad roll. The closest number to their Body (which was 2) is 4, so they reduce their Body by the difference of 2 and 4, which is 2! Tough luck, Alex. Alex's Body is now 0, which means they suffer Trauma. Luckily, their Bonds are in reasonably good shape. Alex has two Bonds: Jane with a rating of 5 and Mary with a rating of 2. Alex rolls 2d6 to figure out how much rating they have to deduct, and they roll: 4, 2. They decide to reduce Mary to a rating of 1 and remove Jane completely. The Trauma they suffered just inevitably pushed Jane away.

Special Rules:

• First Aid: Within 1 hour of losing Body, Investigators can attempt to give First Aid. To do so, they have to spend 20 minutes taking care of the injury and restore a point of Body. This requires the necessary supplies that are used upon use. (1 Preparation, See Preparation)
• Set Up: Only when time is of the essence, Investigators can spend some time to get into a good position. This can mean that they aim, or that they gather their strength before rolling an Action. Only under time pressure, when asked what to do, Investigators can choose to just prepare their next Action. If they do so, they take +1d or +1 Effect on their next Action-roll.
• Drugs: The mind is a wonderful place, and can be biologically manipulated to keep going when it's about to break. Upon taking (the relevant kind) of drugs, an Investigator regains 2 Mind. However, upon changing the scene, they lose those points again, potentially suffering Trauma in the process. To take drugs, one has to have them. (1 Preparation, See Preparation)
• Teamwork: Sometimes, when the GM deems it appropriate, many rolls of different Investigators can be surmised by one Action-roll of an Investigator. For instance, when all of them attempt to sneak into some place. In that case, only the leader of the Action rolls, but every Investigator is in line of fire for potential consequences.

 

Investigator Creation:

Action ratings: 

The Actions Investigators use are verbs, things the Investigators do (to overcome obstacles), not attributes they have. People can be good at noticing things for all kinds of reasons, but we don't really care about why they are good at it in this game.                     

The Investigators can distribute 22 points of rating on the following Actions (max. 4 in one Action):

• Notice (awareness, hearing, reflexes, searching)
• Assess(interpretation, estimation, insight, analysis)
• Move (Moving oneself and or objects from place A to place B, including sprinting, climbing etc.)
• Charm (Persuasion; being nice and chummy with people)
• Coerce (Intimidating, commanding, and shouting)
• Deceive (Lying, trickery, disguise, misdirection)
• Procure (Buying things, finding the right stores, places, information, and people)
• Fix (Making things work again, machines or biological)
• Fight (Fisticuffs and melee weapons)
• Shoot (Shooting)
• Stealth (Being inconspicuous, evading notice, hiding things)
• Endure (Doing things you really don't want to)
• Focus (Keep a clear mind, despite unnatural and natural horrors.)

Stats:

All Investigators start with the following statistics, though some of them can be customized further through their Perks.

• Body 6
• Mind 6
• Bonds 3
• Preparation 7

Bonds:

Investigators can create a number of Bonds, i.e., touchstones and anchors, to keep them sane and working, equal to their related stat.

    

    When creating a Bond, first assign them a Name and a sentence-long description, telling us who they are. The description provides their expertise and the avenue through which they can help the Investigators.

Bonds are important. They are the people in the life of the Investigators who are actually willing to help them.

Every Bond starts with a rating of 4. The rating of Bonds can be used in two ways.

• During an investigation, Investigators can ask for favors from their Bonds. To do so, they reduce the rating of that Bond by 1, but get what they asked for (given the Bond can actually help); no roll needed, though the Bond has to be reached narratively.
• The rating of Bonds is used as a buffer before the Investigator becomes unplayable. (See Trauma)
• During Downtime, Bonds expect to spend time with. Investigators can pursue their own interests and ignore their Bonds, or spend time with those who used to matter in their lives.

Preparation:

Investigators have stuff. However, we don't keep lists. To simulate their planning and the stuff they 'always already had' on them (they can find more things during play, of course), we use the Preparation stat. Equipment opens up the possibility to do things: you can't shoot a gun if you don't have one. If you want to lockpick a door without a proper lockpick, you might have -Effect.

Items of a Fine Quality always give a bonus. Items that can only be used once give +2 Effect. Small weapons automatically give +1 Effect, and large Weapons automatically give +2 Effect. Armor, such as a bulletproof vest, counts as large and gives +1d on Body-rolls when applicable.

    During play, every Investigator can 'create' a number of items they already have on them equal to their Preparation rating. Investigators have to make up where they got the item from (they can't just generate a shotgun from nowhere; the shotgun might be in their car). However, we use Procure to buy things during play. Spent points of Preparation refresh every time the Investigators get time to restock their supplies. Investigators all have access to small appliances of ordinary life, such as lighters, watches, keys, some money etc.

Calculating the cost to have a prepared item goes as follows:

Size:

Small: 1 (handheld)

Large: 3 (larger than that)

Illegal: +1

Expensive: +1

Fine Quality: +3 (gives +1d or +1 Effect)

One-time use: +0. (Can only be used once, but gives +2 Effect)

Perks:

Investigators get to distribute 13 points:

• (1/3) Outdoors-Kid: For 1 Point, the Investigator can always find North, for 3 points, the Investigator can survive outdoors for an infinite amount of time.
• (1/2/3) Good Reputation: The Investigator gets 3 points of Reputation that can be spent to get +1d on social Actions that do that relate to what people might have heard about them. This pool refreshes every session.
• (1) Linguist: The Investigator can speak an additional language. Can be taken multiple times.
• (2/4) First Aid Expert: Once/twice per session, the Investigator can attempt to temporarily Fix the Body of another Investigator. The target heals an amount of Body = the Effect of the Action.
• (2/4) IT-Expert: The Investigator gets +1 Effect when interfacing with a computer. For 4 points, they also get +1d when doing so.
• (2/4) Silent: The Investigator gets +1 Effect to avoid being heard. For 4 points, they also get +1d.
• (2) Veteran: The Investigator can see mundane atrocities without having to endure.
• (2/4/6) Know-it-all: 1/2/3 times per Session, the Investigator can provide a useful bit of information from their field of education (as determined by the player). Whenever people use that information for action, they get +1d (does not stack).
• (2)  Well prepared: The investigator starts with +1 Preparation. Can be taken up to 5 times.
• (2) Criminal: The Investigator has easy access to the criminal underground. When rolling to procure illegal goods, take +1 Effect.
• (2) Contortionist: The Investigator can crawl through small spaces and contort themselves in ways not thought possible.
• (2) Secret Identity: The Investigator gets +1d whenever they try to hide their true identity.
• (2) Academic: The Investigator chooses a field of study and gets +1d to know things in relation to that field.
• (2) Innocent-looking: +1 Effect on rolls to de-escalate situations.
• (2) Iron stomach: The Investigator can eat lots of things that might make other folks sick and gets +1d to Endure poisons and +1d on Body tests vs poison.
• (2) Athletic: The Investigator has +1 Effect on rolls to run or jump and on stamina-related tasks.
• (2) Juryrigger: The Investigator can make a machine that's normally just done with the world, and continue until the end of the scene.
• (2) Hawk-eyes: The Investigator's eyes have a regular Effect on longer distances.
• (2) Engineer: The Investigator has to select a specialty for the Fix Action. When the Investigator Fixes their subject, they get a +1 Effect.
• (2) Book Worm: The Investigator gets +1d to research in a library.
• (2) Animal-lover: The Investigator can practically speak with animals (not really, but almost), and animals don't like to hurt them.
• (2) Lucky: The Investigator gets 1 use per session, expending a use after any roll, they can roll an additional d6. Only once per roll and can be taken multiple times.
• (3/6) Trained: The Investigator gets +1 Effect for combat. For 6 points, they also get +1d.
• (3) Scary: Take +1d to scare or intimidate people.
• (3) Official: The Investigator gets +1d to manoeuvre bureaucracies.
• (3) Hotshot Driver: +1d to drive vehicles.
• (3) Likeable: The Investigator starts with an additional friend.
• (3) People Person: The investigator's friends start with an additional rating point.
• (3) Reflexes: When reaction speed is in question, the Investigator gets to react first.
• (3) Sweetheart: The Investigator takes +1d on all actions against people they had some intimacy with.
• (3) Busy-body: The Investigator has +1 Downtime Action.
• (3) Night-owl: The Investigator can see pretty well in (not totally black) darkness, and you are good with little sleep.
• (3) Sucker for Pain: The Investigator gets +1d to resist pain.
• (3) Occultist: The Investigator gets +1d to study and use dangerous tomes.
• (3) Anchored: Once per session, the Investigator can roll a Mind Test again.
• (3) Feline Grace: The Investigator gets +1d to keep balance.
• (3) Enlightened: The Investigator starts with knowledge of the Mythos and can resist with Mind to recall Information about it. Additionally, they have -1 max. Mind but take +1d when casting spells or when resisting the Mythos with Mind.
• (3) Well-Connected: The Investigator gets +1d to procure people.
• (3) Fast Recovery: The Investigator gets +1 Effect when using the Recover Downtime-Action.
• (3) Nimble: The Investigator gets +1d for tasks involving sleight of hand, like magic (the non-spellcasting kind) or pickpocketing.
• (3) Martial Arts: The Investigator takes +1d when they fight without attempting to deal damage (like, when they try to disarm, grapple, knock someone prone etc.)
• (4) Tough-skinned: The Investigator takes +1d on Body rolls. (This doesn't change the stat they need to hit with their roll.)
• (4) Iron-willed: The Investigator takes +1d on Mind rolls. (This doesn't change the stat they need to hit with their roll.)
• (4) Survivor: The Investigator can take an additional Trauma.
• (4) Well-Off: The Investigator has +1 on Preparation and +1d to procure things with money.
• (4) Photographic Memory: It does what it says.
• (4) Strong: The Investigator has +1 Effect on Move and Fight Actions that involve muscle power.
• (4) Charismatic: Choose one Action from either Charm, Deceive, or Coerce. The Investigator gets +1 Effect whenever they use the Action.
• (4) Talented: The Investigator gets an additional point to distribute on their Actions.
• (4) Wing Man: Help of the Investigator gives +1d as well as +1 Effect (instead of only one).
• (5) Assistant: The Investigator has another PC that helps them. The Assistant has all Actions on 0, except one, which is on 2.
• (6) Medium: The Investigator has a supernatural sense to notice Mythos activity.
• (6) Trained to Kill: The Investigator takes +3 Effect on all Actions that attempt to murder someone.
• (7) Sixth Sense: The Investigator can always tell when someone is lying (i.e. when someone is saying something they know is not true, in order to deceive).

Downtime:

After every investigation, the Investigators can take two Downtime-Actions. Every Downtime-Action can only be taken once per Downtime.

Basically, we fill Clocks during downtime. I provided the following Clocks, but the GM can make up new ones depending on what the Investigators want to do in the fiction. Furthermore, at the start of Downtime, reset Body and Mind to 6.

• Improve: If you don't have a Clock for this Downtime-Action, create a related 4-Clock. Otherwise, keep working on the old one. Roll Procure. On a 1-3 increase, the Clock by 1 and reduce the rating of a Bond by 1. On a 4-5, increase the Clock by 1. On a 6, increase the Clock by 2. Once the Clock is full, the rating of an Action increases by 1 up to a max. of 6.
• Make new friends: If you don't have a Clock of this Downtime-Action, create a related 3-Clock. Otherwise, keep working on the old one. Roll Charm. On a 1-3 increase, the Clock by 1 and reduce the rating of a Bond by 1. On a 4-5, increase the Clock by 1. On a 6, increase the Clock by 2. Once the Clock is full, create a new Bond with a rating of 1d3.
• Study: Roll Assess. On a 1-3, get 1 Perk point and reduce the rating of a Bond by 1. On a 4-5, get 1 Perk point. On a 6, get 2 Perk points
• Responsibilities: Increase the rating of a Bond by 1d3.
• Disappear for a couple of days: Roll Move. On a 1-3, create a Mind-buffer of 1 and reduce the rating of a Bond by 1. On a 4-5, create a Mind-buffer of 2 and reduce the rating of a Bond by 1. On a 6, create a Mind-buffer of 2. The Mind-buffer does not get rolled but functions as a shield. It gets used before the Mind gets directly reduced.
• Make some money: Increase Preparation by 1. Reduce the rating of a Bond by 1.
• Read what you shouldn't: See next section. This requires the object-to-be-read. Mind lost during this Downtime-Action is not recovered before the next mission.
• Research: Roll Notice. On a 1-3 reduce the rating of a Bond by 1. On a 4-5, discover a relevant object, person, or piece of information you are attempting to find. On a 6, increase the Clock by 2. Once the Clock is full, create a new Bond with a rating of 1d3. Reduce the rating of a Bond by 1.
• Acquire an asset: The Investigator gets access to a specific piece of equipment, location, person etc. If the asset is difficult to acquire, open a 2-Clock as with Improve or Make new Friends and start filling it by 1 per time you take this Action. Reduce the rating of a Bond by 1.

Additionally, there might be Clocks already in play from the investigations. Those can stay in play, and the Investigators can influence them by spending Downtime-Actions also. For that, they have to say how they do it and then roll an Action. They change the Clock by their Effect as with other Downtime-Actions.

I suggest not just playing out any downtime abstractly but laying plot-hooks and opportunities for Action-Rolls, if the Investigators have the opportunity to find some stuff out during the fiction: let them.

Magick:

As in other Cthulhu-esque games, there are ways to engage the Mythos as Investigators that do not involve running, hiding, or shooting. Some cultists might have access to Magick, and when finding dangerous tomes, the characters might also get access to not only knowledge but also spells.

In case the Investigators get hold of dark tomes and are able to learn some spells, the best way I found to handle them is idiosyncratically. Every tome should have its own rules, dice rolls, and every spell should work slightly differently from all others. A general scheme, which should be filled out more dutifully by the GM, could look like so:

Acquiring dangerous knowledge through tomes and the like requires an Action-roll. Most likely, Assess, Endure, or Procure; but others are thinkable depending on the work. Afterwards, there should be some kind of roll with Mind with a modifier depending on how bad the tome is. Knowledge is dangerous. Having read the tome should always give a narrative benefit: now the Investigator knows something relevant they didn't before. Maybe the weakness of a horror, or maybe a new clue on where to go next.

Tomes could include spells. I think learning a spell should depend on the spell and the tome. If it's a quick chant, maybe the Investigator can learn it just while studying the tome, with no further roll needed, but maybe it's a hidden ritual that has to be uncovered with more rolls.

Spells that are uncovered can be used (who would have guessed). Spells should be handled individually, also. There are different axes that can be modified to create an individual spell.

Magick: What does the spell actually do? I think the best spells have effects that are explainable otherwise. Only powerful Magick should be visibly magical.

Action: Does the spell require an Action to cast, or does it just work?

Mind: Whenever an Investigator casts a spell, they must roll with Mind. Casting spells destroys the mind. However, powerful Magick might even remove some dice, max. 3.

Body: In addition, some Magick might require a Body-roll since it drains the life of the caster.

Time: How long does casting the spell take? A few seconds, hours, days? Is it a ritual?

Ingredients: Does the spell require special preparation? Some ingredients are easy to gather, but for some, the Investigators might need to spend time, money, and effort to gather.

Memorization: Can the spell be learned by heart, or does the caster require notes of the incantation?

I think the best spells are just designed by the GM, for the book it can be found in, and for a specific investigation or campaign.