#set page(
  paper: "a4",
  header: [
    #set text(8pt)
    Open D12 | Core Rules | v0.0.1
    #h(1fr)Feedback: https://github.com/dice-punk-press/open-d12/issues
  ]
)

= Open D12 Core Rules

== Alpha Release v0.0.1
This is an early release of the core rules. Everything works but
we're actively collecting feedback and improving things. There
may be big changes to come. Check the feedback link in the top
corner for the latest updates or to leave feedback. Thank you,
your feedback makes the game better.

== Introduction
#text(style:"italic")[Open d12 is a rules system for creating
table top role playing games. It is not a game in itself but a
set of rules that can be used to create a wide variety of games.
The rules are designed to be simple and flexible, allowing
players and narrators to create and play games in a wide variety
of settings and genres.

The core rules are minimal but complete. There are number of
extensions that can be added to the core rules to create more
complex and detailed games.

The best way to think of Open d12 is as a set of recipes for
creating games where some of the ingredients will need to be
decided by the authors.]

#outline(indent: auto)
#pagebreak()
#columns(2)[
== Definitions
/ Setting: the world in which the game takes place, including
  the culture, technology, geography and history of the world
/ Scope: the breadth of roles and activities that the players
  will be able to take on in the game
/ d12: a 12 sided die
/ Narrator: the Narrator is the person who facilitates the game
/ Characters: players create and take on the role of characters
  in the game
/ Skill Group: a skill group represents a set of skills that are
  related to each other, players invest points into skill groups
  to represent their characters' abilities
/ Skill: a skill is a specific ability that a character has,
  skills are grouped into skill groups
/ Roll: a roll is the act of rolling a d12 to determine the
  outcome of an action
/ Result: the number used to determine the outcome of a roll
/ Extension: an extension is an additional set of rules that can
  be added to the core rules
/ Chances: character's have chances, this is a resource that
  allows them to avoid serious harm or negative consequences
/ Fun: in open d12 fun comes from exploring the game world and
  your character and from failure as well as success

#set heading(level: 1, numbering: "1.1")

= Basic Equipment Needed
- One or more d12s (more recommended)
- Paper and something to write with
- A copy of the rules

= Game Rules
To create a game using Open d12 you will need to decide on the
following:
- The *setting* and *scope* of the game
- The *skill groups* and *skills* that will be used when
  creating characters
- Which, if any, extensions you are using
- How you will guide players through character creation and
  playing the game
- How you will support the Narrator in facilitating the game

== Setting and Scope
The *setting* and *scope* inform everything else. Being clear
about the setting and scope will help you to make decisions
about how to implement the rules and make the game easier to
design, facilitate and play.

*Example:* _If you pick a steam-punk fantasy world as your
setting think about whether the scope of the game will be 
focused on anyone from that world or focused on the
people who crew and maintain the airships that are the primary
form of transport._

Broader scopes are not necessarily better. A more focused scope
allows for clearer mechanics and story telling. However, it's
possible not everyone will want to play a game with a very
specific combination of setting and scope. At the end of the day
it's import to focus on what you will enjoy creating.

== Skill Groups
In open d12 characters have a number of *skill groups*. These
represent a character's broad areas of expertise. When creating
a character players invest points into these *skill groups* to
represent their character's abilities. The points invested into
a *skill group* typically determine the *skill level* for all
of the skills belonging to that group.

The minimum value for a *skill group* is one and the maximum
value is nine. You may wish to further restrict the maximum
value a character can start the game with. A character with 9 in
a skill, especially with a *bonus die* will succeed about 90% of
the time.

It is recommended you have between three and six *skill groups*
in your game. The more skill groups you have the more complex
your game will be.

*Example:* _If you are making a simple 'sword and sorcery' game
then you might decide on the following skill groups: Might,
Finesse and Knowledge._

== Skills
A *skill* is a specific ability that a character might want to
perform. *Skills* belong to a *skill group*, with related skills
belonging to the same group. A character's *skill level* is
typically determined by the number of points they have invested
in the *skill group*.

It is recommended that each group has the same number of skills
and that you have between two and four *skills* in each
*skill group*. The more skills you have the greater the chance
they wont all be used. However, too few skills can get in the
way of players being able to create the characters they want.

*Example:* _Building on the simple example above you might
decide to have the following skills belonging to the following
groups. Might: Attack, Defense. Finesse: Aim, Stealth.
Knowledge: Arcana, Lore._

=== Specialization
To make characters more unique they can specialize in one or
more skills. When a character specializes in a skill they gain a
*bonus die* when rolling that skill.

= Character Creation
The basics of character creation involve determining how many
points are invested in each *skill group* and if the character
is specialized in any *skills*.

It is also important for characters to have a name, a
description and a background that ties them into the setting.

You will need to decide how many points are available for
players to invest, how many can be invested into any one skill
at the start of the game and how many skills can be specialized
in.

*Example:* _For our simple 'sword and sorcery' game we might
decide that players have 9 points to invest in their character's
skill groups and that they can invest a maximum of 6 points into
any one group. As skill groups start at 1 this means the maximum
starting value for any skill group will be 7. We'll also let
players pick 1 skill for their characters to specialize in._

You may want to tie specialization in certain skills to a
particular background or profession. This isn't covered in the
core rules but there are extensions that go into more detail.

= Playing the game

== The Narrator
The role of the Narrator is to facilitate the game. Their goal
is to create a fun, challenging and engaging environment for
the players to explore and tell stories in. They have three main
responsibilities: 

*Describe the game world and non-player characters.* The
Narrator describes what is happening in the part of the game
world the players are interacting with and how it looks, feels,
sounds, smells, and tastes. They also describe the actions and
appearance of any non-player characters who are present. They
also answer questions from the players about the game world and
non-player characters, although they may choose to keep some
information secret or require a *roll* to reveal certain pieces
of information.

*Provide just enough direction to move the story forward.* The
Narrator provides one or more 'story hooks' to give the player
characters a reason to act and provides a source of challenge,
story-conflict and tension. The Narrator needs to make
characters earn their successes and feel their failures. They
also need to prevent characters from getting totally stuck.

*Use the game rules (and their own judgement) to determine the
outcomes of actions.* The Narrator helps the players to navigate
the rules and determines what happens when a roll succeeds or
fails. It is important that the Narrator acts fairly and
consistently when applying the rules and determining outcomes
and that they generally act in the interests of keeping the game
fun, challenging and engaging.

== The Players
The role of the players is to take on the role of a character in
the game world. Their goals is to explore the world and their
characters by interacting with the game and the rules.

Players ask the Narrator questions about the game world and
decide what their characters do, say and try. They also decide
_how_ their characters try to do things.

Players don't have specific responsibilities but it is
recommended that they prefer working together to solve problems,
have a high level understanding of the rules and their
characters and, most importantly, have fun.

== Rolls and resolution
When a player attempts something uncertain or risky the
*Narrator* will ask them to make a *roll* using the *skill* that
most closely matches the action they are attempting. The player
will roll one or more d12s (based on the *bonuses* and 
*penalties* involved in the roll) to determine the *result* of
the roll.

The *result* is compared to the *skill level* of the *character*
for the chosen *skill*. A result of equal to or less than the
skill level is a *success*, a result higher than the skill level
is a *failure*.

*Bonus Dice*: If the *roll* involves one or more *bonus dice*
then the player rolls a number of d12s equal to one plus the
number of bonus dice they have and uses the lowest number on any
of the dice as the *result*.

*Penalty Dice*: If the *roll* involves one or more
*penalty dice* then the player rolls a number of d12s equal to
one plus the number of penalty dice they have and use the
highest number on any of the dice as the *result*.

*Bonus and penalty dice*: *Bonus* and *penalty dice* cancel each
other out. For example if a *roll* involves two penalty dice and
one bonus die then they player would make the roll with one
penalty die.

*Neutral Rolls*: If the *roll* has no *bonus* or *penalty dice*
then the player rolls a single d12 and uses the *result*.

== Determining bonus and penalty dice
*Bonus dice* can come from three sources. A character may be
*specialized* in a *skill*, granting them a *bonus dice* when
rolling that skill. The *Narrator* may grant a *bonus dice*
based on the in-game circumstances surrounding the *roll*, for
example preparation and planning by the characters or having the
right tools for the job. Finally some items or conditions may
grant situational *bonus dice*.

*Penalty dice* come from the difficulty of a given role, either
because the task is inherently difficult or because the specific
situation is making things more difficult. The Narrator
determines how many *penalty dice* are involved in a given roll.

== Danger, threat and chances
In the core version of the rules each character has three
*chances* to avoid serious harm or negative consequences.
Characters are typically given a chance to perform a *roll* to
avoid harm. If they fail the *roll* then they lose a *chance*.
If they lose all of their *chances* then they are out of the
game - this could mean they are dead, captured, unconscious or
otherwise unable to continue, depending on the setting.

*Characters* do not lose a *chance* every time they fail a roll,
only when the *Narrator* determines that it is appropriate.

=== Regaining chances
The *Narrator* may allow characters to regain *chances* by
resting, healing or through other in-game actions.

== Non-player characters
Non player characters are important for making the game world
feel alive and can be a good way to provide hints and direction
to the players.

The *Narrator* creates and controls non-player characters.
Non-player characters use the same rules as player characters,
they have *skill groups* and *skills* and make *rolls* to
determine if their actions are successful. These rolls are made
by the *Narrator*. The *Narrator* can decide if these rolls are
made in secret or in the open.

== Items
The core rules do not cover items in detail. However, players
and the *Narrator* should consider the following things when
dealing with items in the game.

As in the real world there should be a limit on the number of
items players can carry and use at the same time. If a character
is carrying too many items then the *Narrator* may require a 
*roll* to determine how well they deal with the consequences of
being over encumbered.

Players should keep track of the items their characters are
carrying and using.

The *Narrator* may award bonus dice (or penalty dice) for having
the right (or wrong) tools for the job. Some things should be
impossible or very difficult to do without the right tools.

== Opposed rolls and combat
If two characters are trying to achieve opposing goals then the
*Narrator* may call for an *opposed roll*. In this case both
characters make a *roll* and the character with the lowest
*result* that is also a *success* wins.

Opposed roles may use the same *skill* or different *skills*,
depending on the situation.

If both characters fail the *roll* then the *Narrator* should
resolve the situation in a way that makes sense for the game.

=== Combat
In the core rules combat is a special case of an *opposed roll*
where one character (the attacker) is trying to inflict damage
on another (the defender) and reduce that defender's *chances*
by one.

Depending on the situation surrounding the roll the defending
character may be able to make a *roll* to avoid the damage.
Typically if the defender knows about the attack and is
sufficiently mobile then they will be able to make a *roll* to
defend themselves.

*Example:* _In our simple 'sword and sorcery' example a goblin
non player character attacks a player character. Both characters
have seen each other and are ready for battle. The Narrator
rolls the goblin's attack skill and the player rolls their
character's defense skill. If both rolls succeed then the lowest
roll 'wins'._

Depending on the scope and setting of the game it may be
necessary to decide which skills can and cannot be used to
defend against each other. For example, could a _defense_ skill
be used to defend against _magic_?

= Running the game
== Starting the game
- Ensure all players understand the basics of the rules and have
  created their characters
- The Narrator and each player establish a *story hook* for that
  player's character, this gives the character an initial goal
  or motivation once the game starts
- The players and Narrator agree any ground rules for the game
  (for example, how long the game will last, what types of
  content and behavior is and isn't appropriate in the game,
  etc)
- The players and Narrator should introduce themselves if they
  don't already know each other
- The Narrator should introduce the setting, describe the state
  of the world at the start of the game and provide any
  background knowledge it is reasonable for the characters to
  start with
- When each player character is first introduced give the player
  a chance to describe their character

=== Story hooks
A story hook is a reason for a character to act. In shorter
games the hooks tend to be obvious and immediate, in longer
games they may be more subtle and complex. The *Narrator* should
provide at least one story hook for each character to give them
a reason to act and to provide a source of challenge,
story-conflict and tension.

== Core gameplay loop
1. The *Narrator* establishes which characters are present in
  the scene and describes the world around them, including any
  non-player characters who may be present and what they are
  doing.
2. The *players* describe what their characters are attempting
  to do and how they are attempting to do it or ask the
  *Narrator* questions about the scene.
3. The *Narrator* continues the plot, either by sharing more
  information with the players or by asking for a roll. If a
  roll is required the Narrator also determines the skill being
  used and the difficulty of the roll.
4. The *players* react to this new information and decide what
  their characters are going to do next, moving the story
  forward.
5. Start again from 1.

== Ending the game
The game ends when the players have achieved their goals or lost
all of their chances.

When the game ends the *Narrator* should provide players with a
sense of closure and an opportunity to reflect on the game. For
example, they might describe what happens to key non-player
characters and how the player characters' actions have impacted
the larger game world.
]