The Rulebook The Gamers
Charactercore Actioncore Gming Worldsofadventure Community
Character Core Action Core Running the Game Worlds of Adventure Community
Skills Basic Combat Gamemastering Paradox title text Designer Blogs
Feats Combat Dice Campaign Building Forum
Gear Environments NPCs Project Dreamscape
Roles Dramatic Interactions Appendix Project Spoof
FX Taint Glossary Ultimate Academy X
Fortune Resources

d20 Advanced (d20A) is a fully-customizable toolbox RPG based on the d20 System. It allows creation of character appropriate for almost all genres of play from different time periods or power level, and features a variety of optional rules to increase or decrease the complexity of gameplay.

Guiding Principle

D20 Icon
The goal behind d20A is to create a toolbox that maximizes options where they matter while keeping the game simple and true to the central d20 mechanic as much as possible. It's very easy to remember how to resolve actions when they all follow the d20 + modifier vs DC model, and this mechanic should be used whenever possible. The goal of this variant system is similar to True20 and d20 Modern in that it seeks to use the core of the d20 System to create a flexible, playable, and fun toolbox with which groups can build just about any game they want.

Using This Wiki

d20A is arranged in a series of Cores and Modules. The most basic rules are found in the two Cores: these are all you need to run simple games using the d20A system. But along with each Core are a set of Modules, which provide more options.


The absolute essentials of d20A are boiled down into two Cores. If you want to play a quick game of d20A, the Character Core and the Action Core provide all the rules you need.

Charactercore Character Core

With the Character Core, you have the rules you need to create a character for a d20A game. The Character Core covers all of the basic capabilities of a character, from the Ability Scores, to Movement, to Size and Senses. With this starting point, you're ready to add Character Modules to expand your game with new options for creating characters.

Actioncore Action Core

The Action Core provides the basic rules you need to resolve challenges in d20A. It uses a simple, d20 roll + modifier rule to determine success or failure on various sorts of challenges, and provides the basis that all the Action Modules plug into.


Beyond the essential Cores, the Modules exist to provide you with additional options for your game. Most modules work entirely independent of one another, where you can pick and choose which ones you wish to include. Some depend on material in other modules, though this is noted at the start of each module.

Each module will also have guidelines at the beginning for how to incorporate it into your game, including how it interacts with other modules:

Redlight This entry gives you important information on what to expect if you choose not to use the module, and how to use the Cores to provide what the module may have been intended to do.
Yellowlight The yellow entry provides guidance for how the module may be used only from the GM side of the game, especially for Character Modules being used to build NPCs but not PCs.
Greenlight The final entry explains how a module may be incorporated in your game, and what sort of changes you can expect with gameplay, especially how it will impact PCs.

Character Module Character Modules

The Character Modules serve to provide options for how players can build their characters.

  • The Feats Module introduces the simple and self-contained feats which are found in numerous module. Feats offer a basic way to customize most sorts of characters relatively quickly, with minimal arithmetic.
  • The Skills Module introduces another basic concept in skills, which are a robust method for customizing characters and resolving challenges.
  • The Gear Module is the last of the basic Character Modules, outlining rules for many common sorts of Equipment, as well as more fantastic Devices and Structures.
  • The Roles Module works with the Combat Dice Module to help give each character in a group a well-defined role in combat, with different approaches available to every type of character.
  • The FX Module is available to groups who want their characters to have abilities that go far beyond what is natural. FX can represent everything from magical spells to superpowers to the gifts otherworldly aliens might possess.
  • The Fortune Module is a final set of options which allow groups to formalize the social contract between GM and players, allowing players to create more three-dimensional and flawed characters who are encouraged to overcome those flaws to rise to the greatest heights of heroism.

Action Module Action Modules

The Action Modules expand upon the Action Core to flesh out different types of challenges, and provide players new was to interact with the world the GM presents to them.

  • The Basic Combat Module provides all the essentials you need for a game where combat will feature heavily, and utilizes a fluid system designed for ease-of-play while maintaining a level of tactical options to challenge players with.
  • The Combat Dice Module expands the Basic Combat Module by giving players an extra edge and an additional resource to keep track of in battle. It's intended for games where combat is intended to be very important.
  • The Environments Module provides some options to expand on the zones described in the Basic Combat Module, but focuses heavily on allowing GMs to challenge players with the environment, making cross-country treks quite interesting.
  • The Dramatic Interactions Module is intended to provide a way for groups to have a relatively simple system to resolve dramatic scenes like chases or social combat.
  • Finally, the Taint Module provides a grittier approach to long-term debility from the darker elements of the world, representing everything from the corruption of evil to the throes of madness to the touch of mutation.


In addition to fully-fledged modules, there also exist smaller "mini-modules" which exist as options to add to a larger module, or ways to change a larger module and tweak it to better suit your group's style of gameplay.

Gming Running the Game

If you plan to be a d20A gamemaster, the last three sections of the book (on running a game, building a campaign, and using NPCs) will be helpful. The advice starts out general, with new GMs in mind, and then tries to offer more specific help with using the d20A system.

Other Helpful Guides

These rules also include numerous helpful visual aides to keep everything organized and accessible.

Designernotebook Designer's Notebook

For greater insight into the thought-process that went into creating the rules of the game, there are numerous Designer's Notebooks throughout the rules.

Gritty Gritty Options

Some groups prefer to make things harder on players, and we've provided Grim & Gritty options that help to create an atmosphere where survival itself is a victory.

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