Open D12

Open D12 is a free and open rules system for creating table top role playing games. You provide the world, settings and ideas and customise the Open D12 rules to best fit your project.

You can use just the core rules to make a simple short play game or add in the optional extensions to make something more complex.

Open D12 is the system we're using internally at Dice Punk Press. You can read about why we're releasing it for free here.

Open D12 Design Goals

• Simple mechanics are better than complex mechanics - for almost everything you roll one or more 12 sided dice
• Avoid special cases and exceptions in the rules - keep if-this-then-that to a minimum
• Minimise the amount of information players need to track and maintain
• Keep the core rules small and easy to underatand
• Trust players and the Narrator (that's what we call the GM) to do what's right for the story - don't over-design or over-specify

Overview

Characters

Characters are defined by how many points they invest into skill the different skill groups (you define these when making your game). Skill groups contain multiple skills (you also define these). Characters can specialise in some skills to gain a bonus dice when rolling that skill (again, you decide how many when you customise the rules).

Rolling Dice

Players roll one or more d12 dice and aim to roll equal to or less than their character's skill level for the skill they are rolling. If a character has bonus dice then they roll that many extra dice and use the lowest number rolled on any single dice. If a character has penalty dice then they roll that many extra dice and use the highest number. Bonus and penalty dice cancel each other out.

Chances and Damage

Each character has a number of chance (we recommend three). When a character takes damage they lose a chance. This represents a lucky escape.  If a character loses all their chances then they are out of the game.

What about...

Along with the core rules there are a number of extensions for adding in things like more detailed combat roles, more structured character creation and additional systems like fatigue or spell casting.

What kind of games can I make?

Anything as long as it's a table top role playing game. You don't need to slay dragons. explore dungeons, find paths or escape eldritch horrors and the stakes can be anything from saving the universe to something far more gentle.

Project Status

Open D12 is in active development, the core rules are released in an 'alpha' state with things like the combat extension coming soon. Developing in the open is important to us. Anyone can make suggestions, give us feedback, contribute to the rules or copy the rules for their own use (even commercial)*.

*Open D12 is available under the CC-BY-4.0 Licence. Details here.

How to get involved

Most work happens on github. You can also comment and give feedback here on itch.