Well well well, look what the shoggoth dragged in.


Apocalypse World

A post-apocalyptic roleplaying game by Vincent Baker which has inspired a whole class of games collectively called PbtA.

Call of Cthulhu (CoC)

A horror investigation roleplaying game based on the fiction of H. P. Lovecraft. First published in 1981 by Chaosium, and now in its seventh edition.

Unlike D&D, Call of Cthulhu has no classes or levels and has an extensive skill list. The default setting is the 1920s, often in the USA, but supplements exist for different periods and locations.

Dice Notation

Dice rolls are expressed in the form NdS, where N is the number of dice to roll and S is the size of die. Modifiers can be given with +M or -M. Usually the values of the dice are summed to get the result.

For example, 3d10+7 means “roll three 10-sided dice, sum them, and add 7 to the result”.

There are two common exceptions:

  • d100, or “percentile dice”. Very few people own an actual 100-sided die, so usually this is done by rolling 2d10 and designating one die the “tens” place and the other the “ones” place. Or equivalently, rolling 10√ód10 + d10.

    For example, rolling a 3 and a 7 is read as 37.

    A roll of 0 on both dice is read as 100.

  • d66, d666, and so on. Similarly to percentile dice, this usually means to roll multiple dice and read them as digits of a larger number.

    For example, rolling a 1, a 3, and a 6 is read as 136.

    Since a d6 is numbered from 1 to 6, the results of a d66 (for example) do not cover all values from 1 to 66.

Dungeons & Dragons (D&D)

The most popular roleplaying game, created in the 1970s by Gary Gygax and Dave Arneson.


An OSR game by Sine Nomine Publishing about being divine heroes in an apocalyptic fantasy world.

Game Master, Dungeon Master, Keeper, Referee, etc (GM)

The player at the table who plays the part of “the world”, rather than controlling a specific PC. The GM will describe the events taking place, decide what happens when outcomes are uncertain and control NPCs. Traditionally the GM will also handle out-of-game concerns like scheduling.

The GM is not opposed to the PCs; they’re not trying to win or to score points against the other players. Even though they have a different role, they are still a player.

Non-Player Character (NPC)

A character in the game world which is controlled by the GM. These will be your shopkeepers, guards, aristocrats, monsters, and so on.

Old School Renaissance (OSR)

A movement to go back to the origins of the hobby which, in practice, usually means games based on early editions of D&D.

Described in the Principia Apocrypha:

The more of the following a campaign has, the more old school it is: high lethality, an open world, a lack of pre-written plot, an emphasis on creative problem solving, an exploration-centered reward system (usually XP for treasure), a disregard for “encounter balance”, and the use of random tables to generate world elements that surprise both players and referees. Also, a strong do-it-yourself attitude and a willingness to share your work and use the creativity of others in your game.

Powered by the Apocalypse (PbtA)

Games inspired by Apocalypse World.

There is no generic “PbtA system”, rather these are games built on the same principles. As Vincent Baker, the creator of Apocalypse World, has said:

Is Apocalypse World an inspiration for your game? Enough so that you want to call your game PbtA? Did you follow Meg’s and my policy wrt publishing it? Then cool, your game is Powered by the Apocalypse. Get with us if you want to use the logo.

PbtA games tend to focus on emulating a specific genre, have player-facing rolls, and use playbooks instead of classes.

Player Character (PC)

A character in the game world which is controlled by one of the players at the table. Usually each player has exactly one PC, which they have exclusive control over, but that is not necessarily the case.


A style of campaign where the action is almost entirely player-directed. The GM creates a world peppered with adventure seeds and interesting characters, but no over-arching plot or linear storyline. The players choose what content to engage with, and the GM prepares what they need for that.


A far-future sci-fi roleplaying game, first created in 1977 by Marc Miller, with two editions currently in print: Mongoose Traveller 2e and Traveller5.

Traveller is notable for being a skill-based game, with very slow character advancement (getting better gear is more common than improving your stats), and using a lifepath character creation system.

Legend has it that Firefly was based on a Traveller campaign.


A science-fantasy roleplaying game, based on the old Fighting Fantasy system, written by Daniel Sell.

Despite not being based on an old edition of D&D, generally considered part of the OSR. The game has backgrounds, rather than classes, and uses a 2d6 roll-under system as its core mechanic.

The default setting is in the spirit of the Dying Earth and Book of the New Sun.

West Marches

A style of play popularised by a series of blog posts by Ben Robbins which set out to be the opposite of a standard campaign:

  • There isn’t a regular session time: the players handle the scheduling.

  • There isn’t a regular party: there’s a pool of players who party up based on their goals.

  • There isn’t a regular plot: the players decide where to go and what to do.

The usual setting is a frontier, where the PCs are explorers, venturing out into the wilderness for gold and glory. They have a safe home base, which every adventure starts and ends in; a partial map (left by previous adventurers); and rumours of what’s out there. Everything else is up to the players.