What Is Starjammer?

Starjammer is the name used on this site to reference “this rule system” but is also a call-back to older-“jammer” named fantasy RPG game settings. Starjammer is exploration and adventure in space – from technological marvels that break past the clouds and careen between planets to strange magics developed to explore new worlds. The core concept is to provide a unique experience for players and GMs by facilitating games that span stars rather than just continents and that visit any world they can imagine. While Starjammer is intended to be a complete set of tools to run Pathfinder adventures in the darkness of the void, it is also intended to be compatible with material from third-party publishers. “Additional Resources” sidebars at the end of each chapter provide suggestions for other titles that players and GMs may find useful for expanding their options.

There are many types of adventures to be found in the void: thrilling big-screen one-on-one dogfights between rebel and imperial vessels; episodic prime-time adventures that center on specific missions and explore humanitarian themes; campaigns that allow players to infiltrate enemy vessels as if they were spacefaring dungeons, fighting off pirates, and clearing decks in search of the treasures of the stars; exploring new worlds, races, and civilizations. There is no practical limit to the kinds of adventures or combinations of elements that can be found in your games.

Likewise, there is no set definition of what a spacefaring adventure will or should look like – they may contain as much or as little magic or technology as players and GMs desire. An adventure may be almost entirely surface-bound with space vessels existing merely to move from one world to another while other campaigns might play out entirely in the void between the stars. The universal constant is that element of the unknown from distant places that few within the setting ever visit.

What becomes known can never be unlearned, and this poses a very real risk to those who better or worse, even the homeworld of the adventurers. Planetary invasion is a very real possibility in the world of Starjammer, as is colonization. The difference is largely one of perspective, but that does not change the reality that it’s the player’s choice in how to approach their adventures in space.

Delving into alien ruins in search of lost magic. Matching wits with corporate technomancers and their robot army in the gritty streets of a space station. Strafing a dragon-crewed attack cruiser with your starship, defending a new colony from deadly alien predators, or making first contact with a previously unknown alien empire. Whether your tools are laser rifles, powered armor, esoteric magic, or simply your powers of persuasion, this game is a game of heroes who change the face of the galaxy, one adventure at a time.

Before you can pick up your arc pistol and blast off toward adventure, there are some key things you need to know about running or playing this game. If you’re already experienced with roleplaying games, feel free to skip ahead.

In this game, you and your friends play the crew of a starship exploring the mysteries of a weird universe. Within this framework, however, there are no limits to the characters you can play and stories you can tell. Will you seek fame and fortune as a corporate mercenary? Perhaps you’re a Xenowarden fighting to protect the ecology of new planets, a mind-reading mystic detective, or an android assassin with a magic sword trying to atone for a dark past. Whatever your mission, you and your team will need all your magic, weapons, and wits to make it through. But most of all, you’ll need each other.

What’s a Roleplaying Game?

This game is a tabletop adventure roleplaying game (RPG): an interactive story in which one player—the Game Master—sets the scene and presents challenges, while the other players each assume the role of a science fantasy hero and attempt to overcome those challenges. By responding to situations according to their characters’ personalities and abilities, the players help to create the story’s plot as the outcome of each scene (called an “encounter”) leads into the next. Dice rolls combined with preassigned statistics add an element of chance and determine whether characters succeed or fail at the actions they attempt. You can think of an RPG as theater: The players are the actors, while the Game Master is the director. But you don’t have to be a skilled actor or storyteller to play the game; just describe what you want your character to do, and let the Game Master and the rules do the rest!

The Players

Before the game begins, players typically invent their own player characters’ backgrounds and personalities. While it’s possible to play multiple characters at once, it’s generally the most fun to have one character per player, so players can really get into their roles. In addition to coming up with character concepts, players use the game’s rules to build their characters’ numerical statistics, which determine the characters’ abilities, strengths, and weaknesses.

During the game, the players describe the actions their characters take. Some players particularly enjoy play-acting (or “roleplaying”) the game’s events as if they were their characters, while others describe their characters’ actions as if narrating a story. Do whatever feels best!

The Game Master

While the rest of the players must create their characters for a game, the Game Master (or GM) is in charge of the story and world. The Game Master is a player, but for the sake of simplicity, she is referred to in this game and other products as the Game Master or GM, whereas the other players are referred to simply as players. The Game Master needs to detail the situations she wants the players to experience as part of an overarching story, consider how the actions of the player characters (or PCs) might affect her plans, and understand the rules and statistics for the challenges they will face along the way.

Many Game Masters find it fun and convenient to run premade adventures, in which the game’s story and mechanical preparation is largely complete. Other Game Masters enjoy preparing original game material, and many use a blend of both methods. Either way, these rules help Game Masters figure out which characters or creatures are appropriate opponents for a given group of player characters, as well as how to adjudicate everything from zero gravity and environmental hazards to what sort of loot PCs should get as rewards for their accomplishments.

During the game, the players roll dice and use their player characters’ statistics to determine how in-game actions are resolved. Much like a referee, the Game Master is the final arbiter of any action’s success or failure, and she can always override the rules if she disagrees with an interpretation or feels a given rules interaction is breaking the mood.

Unlimited Adventure

A roleplaying game can be played for as long as the Game Master has an ongoing story she enjoys exploring and advancing with her players. This means the game might last for a few hours, if the story is short and self-contained, or it might last several years. Each time the Game Master and players sit down to play, it’s called a game session—most sessions last several hours. Games generally consist of several linked sessions that together form a complete story, called an “adventure.” Short adventures that can be played in a single session are commonly referred to as “one-shots,” while games that last many sessions or contain several linked but distinct adventures are called “campaigns.”

What Does this Site Provide?

This site contains all the information you need to play, whether you’re a player or a Game Master, including information about the different core races from which you can choose, and classes that determine your character’s skills and abilities.

Beyond information about character creation, this site also contains the rules you’ll need to play. Tactical combat, movement, and related rules are an important part of this game, as is starship combat. It’s a good idea for players to review these rules when learning how to play, and it’s key for Game Masters to understand them so that gameplay and adjudication can flow smoothly.

GM rules such as common environments, hazards like traps and poisons, instructions for building encounters and preparing and running games, and more are found in the Game Mastering section. Rules are also included which explain how to incorporate legacy material (content from the Pathfinder RPG).

Besides this site, you need just a few things to play and run a game. Most importantly, you need a prepared Game Master and players with characters they’ve created ahead of time. You also need pencils and a set of polyhedral dice. Each die is referred to using a “d” followed by the number of sides it has (so a four-sided die is a d4). You need at least one d4, d6, d8, d10, d12, and d20, as well as a set of percentile dice (“d%”) that generates a number from 1 to 100 (this can be simulated with two 10-sided dice). You also need a Tactical battle map with 1-inch squares and a starship battle map with 1-inch hexagons, as well as tokens or miniatures to represent your characters and ships.

Some Basic Concepts

To make the best use of this site, you’ll want to be familiar with several key terms and abbreviations. These are used throughout the book, and many are common to tabletop roleplaying in general.

1d6, d20, etc.

These figures are abbreviations for die rolls and indicate which dice you roll to determine a variable number, such as the amount of damage a weapon deals. The first number tells you how many dice to roll, while the second number tells you the number of sides the die or dice must have; if there’s no first number, just roll one die. For example, “roll 2d8” means that you must roll two eight-sided dice, and “roll a d20” means you must roll one 20-sided die. Occasionally, you may need to roll a d3; if you don’t have a three-sided die, you can roll a d6 instead—treat a roll of 1 or 2 as a 1, a roll of 3 or 4 as a 2, and a roll of 5 or 6 as a 3.


This game has many game terms that are typically expressed as abbreviations, including HP (Hit Points), SP (Stamina Points), and RP (Resolve Points). If you miss or forget what an abbreviation means, they’re explained in the glossary.

Armor Class (AC)

This is a number representing how hard it is for an enemy to strike your character in combat. A character has two Armor Classes: Energy Armor Class (EAC) and Kinetic Armor Class (KAC).

Attack Roll

An attack roll is a d20 roll that represents your character’s attempt to strike another creature in combat.


A check is a d20 roll that may or may not be modified by your character’s statistics or another value. The most common types are skill checks and ability checks (which determine whether you successfully perform a task), and initiative checks (which determine when you act in combat).


Typically, references to combat refer to Tactical combat between individual characters, which takes place on a square-gridded battle map. Combat can instead refer to starship combat, which uses a hex map.


A creature is an active participant in the story or world. This includes player characters (PCs), nonplayer characters (NPCs), and monsters.

Difficulty Class (DC)

This is the target number a creature must meet or exceed when attempting a check in order to accomplish a given task.


An encounter is a situation that presents characters with a challenge. This could be a roleplaying challenge where they need to get information, a physical battle, a trap or puzzle, or anything else that requires players to use their wits or their characters’ statistics. Characters typically earn experience points for completing encounters.

Experience Points (XP)

Often just called “experience,” this is a way of tracking your character’s increasing expertise gained as a result of overcoming challenges. When characters earn enough experience points, they advance in level, or “level up” (see Leveling Up).

Game Master (GM)

The Game Master is the player who adjudicates the rules and controls the various elements of a story and world that the players explore. A GM’s duty is to provide a fair and fun game—she wants the other players to ultimately succeed in their goals, but only after much heroic striving and danger.

Hit Points (HP) and Stamina Points (Sp)

Stamina Points represent how much damage you can take before you’re actually hurt, while Hit Points represent how badly hurt you can be before you fall unconscious or die. Stamina Points are lost before Hit Points and are much easier to regain.


A level is an indication of relative power within the game. There are several types of levels. Class level is the number of levels of a specific class that a character has. Character level is the sum of all of the levels a character has in all of her classes. Level can also refer to a Spell’s level, an item’s level, or another scaling mechanic that falls within the framework of the game’s rules.


A modifier is a number that is added to a roll such as an attack roll, saving throw, or skill check. It can be positive or negative.


A monster is a nonplayer character. In general, monsters are too strange or unintelligent to be player characters, or are prevented from being them for other reasons. A monster might be a player character’s opponent or ally, or serve any other role.

Nonplayer Character (NPC)

A nonplayer character is controlled by the GM for the purpose of interacting with players and helping advance the story.

Player Character (PC)

This is a character controlled by a player.


Describing a character’s actions, often while play-acting from the perspective of the character, is referred to as roleplaying. When a player speaks or describes action from the perspective of a character, it is referred to as being “in character.”


In Tactical combat, a round is a unit of time equal to 6 seconds in the game world; every character who is able to act gets a turn once per round. In starship combat, rounds consist of three Phases of actions and don’t correlate to a specific amount of time.

Saving Throw

A saving throw is a d20 roll representing your character’s attempt to avoid or reduce some harmful effect.


Tier indicates scaling and is similar in meaning to “level”; it is used for computers and starships, as well as other elements.

Overview of Play

Building a basic understanding of gameplay will help you absorb the game’s mechanical details. The following are common aspects of play.


Anytime you’re speaking for your character or describing her actions but aren’t in combat, you’re roleplaying. This could be haggling with a trader, describing your plan to sneak into a research station, or just having a conversation with another player “in character.” These situations often require skill checks, in which a player rolls a 20-sided die and adds her modifier from the appropriate skill, but they can also involve Spells or other special abilities. Sometimes roleplaying may progress into Tactical combat. Game Masters should encourage players to be creative and resourceful during roleplaying, while also ensuring that their actions have consequences—don’t insult an excitable crime boss unless you’re ready to defend yourself!


This game is primarily a space opera, and exploring and experiencing new worlds are key parts of the game. Exploration might involve a single space station, a new and alien planet, a faraway Solar system, or the vast reaches of space. It might involve any aspect of roleplaying, but it always involves the GM describing the new and exciting scenes the PCs uncover and with which they can interact. Cultures, environments, and other wonders and hazards vary wildly when PCs explore new places.

Tactical Combat

When the PCs confront or are accosted by a creature or character, the game shifts to Tactical combat. Tactical combat involves characters moving around a Tactical battle map, attacking or using magic and other special abilities, and defending themselves from their enemies. In this game, attacking generally involves rolling a 20-sided die, adding modifiers to the result, and comparing the total to enemy statistics such as Armor Class to determine whether a target is hit. When their attacks hit, characters deal a variable amount of damage depending on their weapons and statistics. But of course, the enemy can do the same thing to them!

Starship Combat

In combat between starships, the PCs pilot their ship around a starship battle map, trying to maneuver into the best position to fire on their enemies without being hit themselves.

Owen the Game Master is running five players through their latest adventure. Rob is playing Player 4, a damaya lashunta mechanic with her pet Drone VV-R9. Judy’s playing Player 5, a shirren envoy who’s fond of grenades. Amanda is playing Player 2, a ysoki technomancer who’s constantly tinkering and is best friends with James’s brooding vesk soldier, Player 3. Rounding out the party is Player 1, Jason’s human Solarian who’s a self-obsessed reality-broadcasting star.