Homebrew RPGs 1: RPG Basics
© 10 May 2011 Luther Tychonievich
Licensed under Creative Commons: CC BY-NC-ND 3.0
other posts


There are many commercial roleplaying games out there, but often the best games are ones you design yourself.


I’ve mostly played Dungeons and Dragons, every edition from the original through 4e except 3.0. I’ve also played entire campaigns of Star Wars Saga edition and Mutants and Masterminds 2e, with scattered forays into Deadlands, FATE, FUDGE, GURPS, Savage Worlds, Shadowrun, True20, and several unnamed house-ruled systems. Given my experience playing RPGs on and off since 1989, and since I’ve always taken a keen interest in the rules that make games tick, I plan to try to distill what, to me, are the most important elements of RPGS into a few simple posts. In this post I will explore the basic underlying concepts of RPGs

What is a Role-Playing Game?

Practically every RPG rulebook ever published has, somewhere on the first or second page, a paragraph or two on what this genre of game is all about. Here’s mine.

A tabletop role-playing game (RPG) system provides rules and structure for collaborative story telling. These rules allow participants to focus on the actions of the characters and have the consequences flow naturally from the resulting rules. They also provides the “‍game‍” element: because the participants cannot fully control the outcome of their plans they become invested in the progress of the characters.

The Participants

Generally, each participant in an RPG takes control of one protagonist, with the exception of one player who takes control of everything else. That one participant, per tradition, is called the game master (GM) GM: a participant who controls the world at large. and controls not only the protagonists’ friends and foes but also the weather, history, narration, scenery, etc. Non-GM participants are called players Player: a participant who controls just one protagonist. and the characters they control are player characters (PCs); PC: a player-controlled character (protagonist). all other characters are called non-player characters (NPCs). NPC: antagonist or supporting cast. Collectively, the PCs are commonly called the “‍party‍”, Party: a collection of characters acting together. a term that also includes any NPC allies that typically appear alongside the PCs. To keep all players involved, it is unusual to have the party split up for any significant time.

GMs often allow the players control additional elements of the story. I’ve heard that GM-less RPGs exist, but I have never personally played one. For example, if a PC has a minor supporting character like a squire, the GM may allow the PC to narrate that supporting character’s actions. Some GMs even allow the players to supply arbitrary narration, including scenery, fluke events, NPC dialogue, etc.

While I’m defining terms, there are typically four divisions of time in an RPG. At the large end is a campaign, corresponding to a novel-length story. Below that is a session, the amount of play that happens in a single sitting often corresponding to a chapter or two. Then comes the scene or encounter, and then finally the round or turn.

Setting, Mood, and Conflict

When it comes to setting, imagination’s the limit. Post apocalyptic science fiction with cockroach protagonists? Pre-lingual Neanderthals who only communicate by grunting? An exact duplicate of Tolkien’s The Two Towers, complete with a visit to the Fangorn while all the trees are in Isengard?

The mood of the game is also important. Is a “‍good game‍” one where everyone laughs a lot? Where they find themselves sweating in genuine fear? Do you want to have a lot of intricate riddles? A huge body count? Should the game be designed for PCs that are struggling peasants, powerful nobles, ruffian outlaws, or superheroes? That mood flavors every line of description of the setting and every second of gameplay.

Finally, and perhaps most imporantly, what kind of conflict are the players trying to resolve, in what way? This deserves an entire post in itself, so we’ll say no more for now.

Capabilities and Chance

Life is chaotic, with many sources of uncertainty and variability. Rather than model these directly, RPGs mash them all into probability, typically expressed as a die roll (though some use cards instead). One of the biggest problems facing RPG designers (though it is not clear that they realize how big it is) is how to assign probabilities to various scenarios.

At some point, somewhere, almost every RPG identifies some capability and assigns each participant some number value for that capability. For example, perhaps Chris has brawn 10 and Dana has brawn 11. Then there comes some contest hinging on that capability, and a probability needs to be assigned. When Dana and Chris arm wrestle, what is the chance that Dana wins? 100% because Dana is more brawny? 50% because 10 and 11 are basically the same? 72.47% because everyone likes the number 72.47?

The answer most designers come to appears to be more-or-less ad-hoc and favor simplicity over accuracy. Also, because stories are assumed to be more fun if nothing is impossible, it is common to include some very small probabilities. In D&D this shows up as the “‍natural 20‍” rules, in Savage Worlds it’s Aces, in Shadowrun 4e it’s the Rule of Six, in FUDGE it’s the natural low chance of a ±4, etc.

I’ll probably devote an entire past to this issue in the future.

The Library

I don’t know of any RPG that calls it such, but nearly every RPG contains a library, which serves as a replacement for the laws of physics. What can a magician do? How long does it take a anthropomorphic jellyfish to chew through a eight inches of concrete? Is an orc a Tolkienesque surly hunchback, a Blizzardesque musclebound greenskin, or a Plinyesque hundred-mile-long sea-serpent?

When designing your own RPG, I suggest only sketching the broad outlines of the library and filling it in as play demands. It is common for RPGs to be published with 50–100 pages of library and the successful ones sometimes add thousands of pages of library in supplemental books. This is not just because libraries need to be large, but actually indicates a secondary “‍game‍” played in RPGs, which I may give a post soon.

Growth and Development

Stories are almost always more enjoyable when they feature significant character development. In writing this typically is shown as personality development. In RPGs it usually shows up as increasing PC skills and abilities; this “‍progression‍” has became so iconic it is nearly the only element of table-top role-playing games that was preserved when porting them to computer RPGs.

Looking for comments…

Loading user comment form…