CD10 Core: Rules Reference

This document is a reference of all the major rules used in CD10. Each section links to the relevant detailed article.

Core Rules

Reference link: CD10 Core

Skill checks and saves

All checks and saves are performed with a D10, with optional Skills and Traits vs a Difficulty (DC) number. The DC is set by the Keeper and is usually not shared with the players. It is kept as a secret goal the player needs to beat with their die, skill and trait. Not all checks include traits or even skills. Most saves, used to resist injury and certain effects usually use neither skill nor trait. If the Result of the player's roll, skill and trait added together is equal to or higher than the DC, they succeed.

Performing a Handguns skill check against a stationary target 35 meters away: (Die) 1D10 + (Skill) Handguns (4) + (Optional trait) Hawkeye (1).

The DC for such a shot is determined to be base 6 (+3 for distance). The player then needs to roll 4 or higher to hit the target because of the skill and trait adding up to 5.

CD10 Core: Skills
Generic article | Sep 28, 2021

CD10 Core rules reference for skills.

CD10 Core: Traits
Generic article | Oct 14, 2021

CD10 Core rules reference for Traits

CD10 Core: Combat
Generic article | Sep 28, 2021

Running combat in CD10 Core.

Glossary of terms

Keeper of Tales (KoT or KT)
The storyteller. The one who runs the narrative and abjudicates rules.
Difficulty (DC)
Set by the Keeper, a number which the player must overcome with their skills.
Result (R)
The combined value of a d10, a skill and optionally a trait.
Outcome (O)
The outcome of a skill check. Can be fumble, fail, status quo, success or perfection.
Excess (E)
The remaining points when Difficulty has been subtracted from the Result.
A choice of how a character is going to act during a round of combat. Most characters have a single action to take in a round.
An involuntary action taken as a response to outside influence. Usually a defensive action.
Most of the time refered to as "PC" for "player character". Can also be "NPC" for "non-player character".
One segment of a combat scene in which everyone gets a turn to act. Lasts 1-3 seconds of in-game time.
A slice of time in which a character takes an action in a round.


Base Die
Skill Checks
D10 + Skill + Trait vs Difficulty


Roll a 0, and also fail the re-roll, or roll -10 below difficulty.
Result is below difficulty, or roll a 0 then beat the difficulty on the re-roll.
Status Quo
Result is equal to difficulty.
Result is above difficulty.
Result is +10 above difficulty.
Alternate fumble
Roll a 0, then another 0.

Common difficulties

3: Easy
6: Normal
9: Challenge
12: Hard
15: Very Hard
18: Send help
21+: You want to do what now?

The Rule of 9

When you roll a 9 on the die, you save that 9 and roll again. You do this until you roll no more 9s. All your rolls are then added together. Should the die fall on 0 after you have rolled a 9 the rule of 0 (automatic failure) does not apply, the die simply counts as 0 value and you stop rolling.


The Outcome of a check or save is what determines what happens. It can be a Fumble, Failure, (Status Quo), Success or Perfection. The Outcome determines just how badly one fails, or how much of a success it is. For simple checks, it's usually enough to determine if it's a Success or Failure (higher or lower than the DC). The other levels are there to help the Keeper with flavour and are used in certain mechanics, such as the physical save of injuries.


Excess is an important mechanic. The Excess is what is left after you have subtracted the Difficulty from the Result. In the above example this is 11-9 = 2. Excess determines things like bonus damage on attacks and sometimes the granularity of checks. Negative Excess (when the Result is lower than the Difficulty) can be used to gauge just how badly one failed, if the Keeper wants.

Most of the time, outside of combat, Excess isn't necessary to calculate exactly. Just determining roughly how high or low the Result was compared to the Difficulty is enough to gauge the magnitude of the Outcome.



Internal modifiers directly affect the player's die roll. A modifier of -3 means that you subtract 3 from the Result of your roll. A modifer of +4 means that you add 4 to your Result. Internal modifiers are things that affect a character directly, like skills (always positive), injuries (always negative) and traits (can be both positive and negative).

It is the responsibility of the player to account for their modifiers when they are making a save or skill check. A player rolls the die, adds all their modifiers and tells the Keeper their Result. The Keeper checks the Result against the Difficulty and tells the player the Outcome, if applicable.


External modifiers are the responsibility of the Keeper and do not affect a character directly. External modifiers affect the Difficulty of a check or save and are things like low visibility, slippery surfaces, rain, loud noises, smoke or similar environmental things.

The Keeper is not required to divulge the modifiers she chooses to use for any check, but should give the player a hint that a thing is made more difficult or easy because of a modifier. For instance, if she's making an Athletics check harder because of a rain-soaked, slippery surface, she might say "The rain has made the street slippery and you find that it's hard to keep your footing. You are performing this check at a disadvantage." She does not have to say exactly how hard she makes it, just that something affects the difficulty.

Hero Points

Hero Points are experience points that players can spend on any check or save. A spent Hero Point allows a player to roll 2D10 for a check or save, or if the hero point is spent after a check is performed, it can be used to re-roll the check.

If the player has spent a Hero Point to re-roll a check and the check is not to their liking, a player may spend a second Hero Point to shift the Outcome one step in either direction, turning a success into a failure or a failure into a success. If a player wants, they may shift a success or failure into a status quo as well.

No more than two Hero Points may be spent in a single session. In order for a player to shift the Outcome of a check, they must spend both their points on the same check. If you run out of Hero Points, be careful as there is now nothing protecting you from the dangers of the world.

Character Creation

Reference link: CD10 Core: Characters


Players create a background story for their characters. They must pick a nemesis and a mentor/influential person. Each player must come up with a relationship to at least two other party members prior to starting the game, unless the Keeper specifically wishes for this to be skipped. This is ensure that all characters have a connection to the party.


Each player chooses a species for their character. Depending on setting this can vary wildly, so each player should either be familiar with the setting or defer to the Keeper for guidance. Be sure to note down the starting traits for the species and/or culture.


Each player picks traits for their character and balances them according to the rules. See the article for details.


Players now select their starting skills and their start levels. Depending on the character's starter level, chosen by the Keeper, the characters get a different number of skills. The default is that each character gets 6 skills at Hobbyist level, 3 skills at Competent and 1 skill at Professional, but should the Keeper wish for it, other starting levels are possible. See the article for details.

It's easiest to pick a bunch of skills from the list that fit your character and then pick a number of them that you want, and finally ranking them according to what you want to be best at. Use your background story to help guide you.

Starting Wealth

Depending on setting, each character gets starting wealth and equipment according to the wealth listing and their traits.


Reference link: CD10 Core: Combat

At the beginning of a round, each participant choose their action for the round, and the actions are resolved in the order of the Keeper's discretion, based on narrative and situation.


Participants in combat can optionally Stress for an additional action but at a cost of -3 Internal Modifier to all checks made that turn.

Action Hold

Participants in combat can hold their action with a condition. They will then act immediately once the condition triggers.


Attacks are performed as a skill check against the combat skill for the weapon in use. Lethality is the potential damage inflicted and is calculated as the weapon's or ammunition's damage value added to any Excess from the attack check. Armor and cover reduces the Lethality.

For melee combat both participants make a combat check, and the one with the highest Excess is the attacker. If the defender also succeeds their check, they add their Block Value to their defenses.

Round structure

  1. Determine the number of actions for players and NPCs (Stressing is declared here)
  2. Every player and NPC decide what actions they want to perform on their turn.
  3. Determine if any character has traits that make them act first. If so, they choose their action first.
  4. The Keeper determines the order in which the chosen actions will play out.
  5. Repeat 4-6 until everyone has spent all their actions. Then begin a new round.

Three Actions

There are three actions a combatant can declare:

  • Maneuver (including dashing)
  • Rest
  • Attack


When taking a maneuver action, a character may elect to Dash, which adds 1 point of Shock, but allows them to move 15 meters instead of 10 meters in combat.


Reference link: CD10 Core: Injuries

Damage to a character is called Lethality and is a potential to inflict harm, not a hard number. The Lethality is the DC for a Save to determine actual wounds.

Injuries are determined with a Save, performed like a skill check without a skill (so just an optional trait and a D10) vs the Lethality of the attack. Lethality is determined by weapon damage and skill Excess from attacker. The Outcome of the save determines the injury. Injuries can cause Shock which will temporarily debilitate a character and also a long-lasting debilitation in the form of Wounds.

Outcome Injury Wounds Shock multiplier
Perfection Scratch 0 0
Success Light Injury 1 x1
Failure/Status Quo Serious Injury 2 x2
Fumble Fatal Injury 6 x3


Experience points are awarded at the end of the session according to Keeper decision and the lists below. Characters can improve skills that they have failed a check on the current session. Characters can also add new skills with their experience points.

Group points

These are examples of points awarded to the entire group. The Keeper and the group are encouraged to come up with specifics that fit their group. However, progression is designed for between two to five experience points per session so that try and maintain that.

  • Participating: Everyone who attends the session automatically gains one experience point.
  • Clever problem solving: The Keeper may award the group an additional point if they solved a problem in a clever or creative way.
  • Role-playing: The point of playing another character is role-playing that character. If the Keeper believes the group has played as their characters, sometimes even to their detriment, the Keeper can award this point.
  • Positive attitude: If the players have had fun and brought a positive mood to the table, the group gets this point. If someone is having a bad day, don't punish them however.

Individual points

These points are awarded to an individual.

  • Extra funny: Someone may say or do something exceptionally funny. The Keeper may award an additional point for that. Be careful with this one as we don't want to turn our sessions in to competitive stand-up sessions
  • Services: During a long session, people get hungry and thirsty. Someone who helps outside of the game either by cooking/ordering food, drinks and someone who helps clean up afterwards is awarded an additional point.
  • Player's award: Each player is allowed one point to give to someone else, if they want to. The player must motivate why they give this point to this person in particular. There is no bad blood for not giving a point.
  • Teacher: A character who has access to a teacher and studies full time gains one experience point per month. Note that this requires full time studies and thus no adventuring.


A character can only carry 12 Kg of equipment on their person without being encumbered. When encumbered, a skill check against Athletics must be made each round of combat (or other physically exerting activity). On a failed check, the character accrues one point of Shock.

Cover image: CD10 Banner by Mizomei


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