RPJ: A Tabletop Roleplaying Engine

RPJ. Where to begin?

What Is It?

RPJ is a free (gratis) and free (libre) roleplaying game engine. The Core rulebook and most first-party modules are or will be Creative Commons-licensed. The resolution mechanic is a 2d6 roll plus a skill level against a target number.

As a roleplaying game engine, RPJ comes in two parts: the Core rulebook, which lays out the rules in setting-agnostic fashion, and modules, which fill in the details of a particular setting. Together, the Core rulebook and a module rulebook make a game.

By way of example, two first-party modules are available alongside the Core rulebook. Use the menu bar at the top of the page to look through the available materials.

Key Features

RPJ charts a course between story-centric games and simulationist games, providing a selection of narrative-first rules on top of a robust rules framework.

Level-less, skill-based character system

RPJ characters are the sum of their skills, yielding a wide-open field for unique character concepts. At the same time, character classes help to guide and focus character builds.

Streamlined combat and damage

Combat dispenses with the need for a grid, instead using large regions to determine range between characters and a simple adjacency system to determine who can hit who in melee combat.

Damage is resolved by a damage save system: when receiving damage, characters roll to shrug it off.

Modern ranged combat rules

Cover and suppressive fire play an important part in modern ranged combat. RPJ includes an optional set of ranged combat rules to simulate them.

Extensibility and Modularity

RPJ is written to permit easy replacement, modification, and expansion of rules. The Core rulebook provides guidelines for implementing the systems defined therein, as well as instructions on creating entirely new systems.

Why RPJ?

Good question!

It’s Open

Not only is the core rulebook licensed permissively, RPJ Sci-Fi is too. So too will be most other first-party rulebooks.

This means unprecedented flexibility for you, the gamemaster or module author. You can mix and match rules, systems, and setting elements however you like.

It’s Free

All of the currently-available RPJ material is available free of charge. This is a major improvement over ordinary for-profit RPGs, where the starting investment is at least two to three books.

Furthermore, you only need four six-sided dice, which you probably already have. Even if you don’t, you can get a set of 36 for $5 or so, and if you don’t have 4d6 lying around somewhere, you can hardly blame that on me.

It’s Generic

RPJ Core makes no assumptions about the genre of its settings, and as such can be used for any genre you can think of. It includes a variety of optional rules you can include or ignore at your pleasure, gives you the tools to build your own optional rules, and provides structure for integrating them with the existing rules.

It’s Complete

RPJ Core is a complete set of rules for roleplaying games, and the open content available in RPJ Sci-Fi and other, as-yet unreleased games provides you fertile ground for wholesale copying. Assembling a new, standalone RPJ-based game or RPJ setting does not take a major exercise in creativity, or won’t, once a wider variety of RPJ systems have been released.

At the same time, because RPJ’s first-party materials include Sci-Fi and Police Cops, both of which are complete, playable modules, you need not do any design work at all if you aren’t interested in doing so.

It’s Tested

This is even more of a stretch than the previous heading, but RPJ has been playtested, and many elements of its design have flowed from playtesting.

It’s Simple

“Ha!” my wife would no doubt exclaim, were she to read this page. Really, though, RPJ is fairly simple by the standards of tabletop roleplaying games, falling somewhere in between D&D 5th Edition and older D&D games, or on par with Warhammer 40K Roleplay or (perhaps) Shadowrun.

The basic action is roll 2d6, add a skill level, and add an attribute bonus. That mechanic is used to resolve nearly everything. It takes fewer dice than the old Star Wars d6 system or even D&D, plays more simply than GURPS, and comes with two (at present) ready-made modules.

Furthermore, first-party RPJ modules come with a selection of cheat sheets and automatic tools which ease the transition to RPJ from other roleplaying game systems, both at character creation and in moment-to-moment gameplay.

It Solves My Problem With Swinginess

One-die RPGs have a problem typically referred to as ‘swinginess’. That is, when you only roll one die, your performance is evenly distributed across the range of that die. When you roll a d20, you average 10.5, but you’re just as likely to perform at that level as you are to perform well below or well above it. This is a psychological problem more than a mathematical one, but it’s still a problem.

In RPJ, you roll 2d6, and when you roll multiple dice, you get a distribution of results where the average is more likely than the outliers. Most of the time, you perform at your level, with the occasional push beyond your abilities or fumble beneath them—frequently enough to be narratively interesting, but not so frequently that the game becomes a story about your luck on dice rolls.

History and Other Background

The Name

Roleplaying games are RPGs. My name is Jay. Ergo, RPJ.

The Beginning

The year: 2008. The place: Rochester, New York. Your intrepid author, a young college student at the time, was griping about having to buy sets of dice to play tabletop games. “Why,” he wondered, “do I need dice, when I have a pocket full of perfectly good, perfectly random coins?”

This absurd non sequitur, plus a a hundred or so hours of dedicated work in the way college students can afford, yielded a Core rulebook and a Fantasy setting. By this time, your author was living with a bunch of people who were all for tabletop roleplaying. A subset of them were even cautiously in favor of trying a weird, untested homebrew system whose existence was justified only by the aforesaid absurd non sequitur.

The fools.

RPJ, in its original form circa 2010, was not a good game. It was clunky, slow to play, and in some cases asked players to flip 40 coins for a single skill roll. This was not ideal. To their credit, those original players stuck with the game, and indeed looked upon it with a great deal of enthusiasm. In spite of their gamemaster (your author again) being as new to gamemastering as he was to game design, and juggling the usual session preparation with minor, or in some cases wholesale, changes to the rules, they nevertheless returned to the table week after week, and were instrumental both in cleaning up some of the rules and improving the feel of the setting¹.

So concluded the first chapter of RPJ history.

The Second Module

The year: 2011. After hard work incorporating the lessons from the first RPJ campaign and further hard work writing a new module, your intrepid author unleashed RPJ Sci-Fi upon his unsuspecting players.

RPJ Sci-Fi, a near-total ripoff of Warhammer 40,000: Rogue Trader, and the associated version of RPJ Core were much streamlined over the state of affairs at the time of RPJ Fantasy. The first really playable RPJ game, RPJ Sci-Fi introduced and tested the Fire and Movement optional core mechanic in RPJ Core, and further refined rules on skill rolling and character creation.

Eventually, RPJ’s testers and author graduated and left left Rochester. Experiments in remote play with 2011’s technology did not go well.

So concluded the second chapter of RPJ history.

Recent History

The year: 2018. The place: Pittsburgh, Pennsylvania. Your intrepid author, having found local friends with a fondness for tabletop gaming, gets back into the hobby a bit, and inspiration strikes. Rewrites of RPJ Core and RPJ Sci-Fi to ditch the coin-based gameplay in favor of 4d6 begin.

A former RPJ player and your intrepid author now work in the same office, and in the course of daily chit-chat, roleplaying games came up. In particular, Larry Correia’s Gritty Cop Show RPG. It was decided that an RPJ cop drama module should be written.

That about brings you up to speed. I’ve now put more than 2,000 hours into RPJ and related content. I hope it brings you a few minutes of joy.

Third-Party Projects

If you have one cooking, let me know, and I’ll link to it here.

Other Resources

The Conclave has an RPJ forum.