Writing ’Verses Expansions

Made to be Expanded

As deliberately hinted at by its title, the ’Verses RPG is designed to be expanded across universe, genre, and game style. These rules provide the core rules that apply to any universe, but hopefully there will be fans of this system who will develop and publish their own expansions and their own universes to explore.

Naming & Referencing Expansions

Expansions to ’Verses may take a number of forms. A given expansion may define additional or alternate rules, expand on existing game worlds, describe pre-written adventures or campaigns, and even define entirely new universes in which to play.

To provide clarity to players and GMs, the following naming conventions are suggested for all expansions:

Expansion Naming Conventions

Type	Description	Example
Adventure	Provides the background, setup, storyline, goals, NPCs, and rewards necessary for a GM and players to play within a given ’Verses Universe.	The Darker Well, a Spellweavers Adventure
Rules Module	A set of related additions or alterations to the ’Verses rules, as well as any supporting information, items, or actor capabilities made possible by the rules changes. Typically dependent only on the core ’Verses rules, although Rules Modules may modify other Rules Modules.	Intoxication, a ’Verses Rules Module
Universe	A self-contained expansion defining a world of play, dependent on the core ’Verses rules, and may reference or include rules expansions & adventures.	Spellweavers, a ’Verses Universe
World Expansion	Additional material that expands on a specific ’Verses Universe, enabling new ways to play and may provide new environments, species, archetypes, and capabilities to explore within that Universe. Dependent on a given ’Verses Universe and may reference or include rules expansions & adventures.	The In-Between, a Spellweavers Expansion

Making Your Own ’Verse

You can build upon the core rules and available ’Verses Expansions to build your own universe. Writing your own adventure or campaign within the world of a ’Verses Expansion is a form of making your own ’Verse. The difference between a custom campaign and a whole game world is merely scale and detail of worldbuilding.

Versioning

It is expected that the rules within ’Verses Core will change over time as new features are developed, game balance is refined, and feedback is incorporated. In order to demarcate and clarify these changes, and to prevent confusion between expansion authors, GMs, and players, ’Verses Core is released under the following semantic versioning^✻ system:

1 Major

. 

0 Minor

. 

0 Patch

Major version

This number increases by one when a new edition is published containing rules or balance changes which alter or invalidate rules in a way which is expected to be incompatible (ie: to "break compatibility") with expansions published for the previous Major version.

Whenever a new Major version is released, the previous Major version will be archived at its highest total version and will continue to be available for reference and continued use by expansions that were designed against it.

Minor version

This number increases by one when a new version is published with rules or balance changes which alter rules in a way which is compatible with the previous version (ie: "backwards-compatible"). Expansions published for the previous version should not generally need changes to continue functioning on top of the ’Verses Core rules.

The Minor version component resets to 0 whenever the Major component is incremented.

Patch version

This number increases by one when a new version is published with text changes, errata, or clarifications which do not impact the functioning of the ’Verses Core rules. No impact on expansions is expected from these changes.

The Patch version component resets to 0 whenever the Major or Minor component is incremented.

 

Learn more about Semantic Versioning at semver.org.

 

Expansions should consider and document which version of ’Verses they are meant to be compatible with. Where possible, Major version updates will include information explaining how expansion authors can migrate their existing expansions to work with the new version.

Contributing

’Verses Core is open-source. Collaboration and contributions are welcome.

Fundamental Mechanics

Writing a fun and successful expansion for any game system requires an additional level of understanding of the fundamental mechanics than is needed for playing the game. The following section explores some of the philosophical and mathematical underpinnings of the ’Verses rules.

Attributes: The Central Framework

The use of the word Core to refer to the four primary attributes (of biological actors) is not accidental. These attributes and the way they fit into the fundamental test mechanics of the game are core to the way the game’s relationship with probabilities and test resolution functions.

In a very real way, everything beyond the core attributes and the test mechanic are specialization and refinement to add color and detail to what is a perfectly functional blueprint. It is possible to conceive of an expansion designed for a kind of gameplay that uses nothing more than a subset of core attributes (for example: TUF & PRW) and the Test mechanic to build a strategy game which represents maneuvers and skirmishes of armies at such a “zoomed out” scale that an entire platoon of soldiers is represented by a single actor.

Core attributes are not considered inviolate for modification by expansion writers, but careful consideration should be taken before adding or altering core attributes, as the indirect effects of such changes can be wide and varied.

Tests & Probability

To achieve the right balance of fun, speed, and expression in an expansion that enables new ways of playing, it is helpful for expansion designers to have a deep understanding of test balance and the probabilities involved in the ’Verses dice pool system.

The minimum and maximum ranges of Rated Values are intentionally kept narrow on the theory that small numbers are easier to reason about. Because Success Targets rarely exceed 5, the primary mechanism for modulating success probability of player and NPC actions is by increasing or restricting dice available to the pool. Abilities and Skills typically add opportunities to increase dice in pools. Other existing mechanisms exist to restrict pool size.

If you’re coming from a system that uses linear probability (where each increase in a die value represents a fixed percent improvement), it’s important to understand just what an increase from 1S to 2S to 5S means. To clarify this, compare the charts below which show the probabilities of achieving 1, 2, and 5 successes with different sized dice pools.

Note that the differences at the minimum extremes are dramatic: There’s a 33% chance of 1 success with 1d6, an 11% chance of 2 successes with 2d6, and less than 0.5% chance of 5 successes with 5d6. Obviously, one cannot achieve 5 successes with less than 5d6. These results represent the truism that training a skill makes easy tasks much more likely, and difficult tasks possible.

The practical effect of this mechanic is that nonlinearity (or the diminishing returns) of training is modeled by the dice probabilities, not baked into task difficulty. Task difficulty and capability increases can easily be mapped to linear increases in values.

In other words: Going from 1 die to 2 does not make an actor twice as capable. Going from 1 to 5 does not make them five times as capable. One can see this represented in the charts above. The second bar (representing a test of 2d6 → 1S) increases from 33% to 55%. Adding a 3rd die brings us to a 70% chance of success and 5d6 → 1S has just 87% chance of success. The additional dice in the pool represent ever-decreasing degrees of improvement.

The following combined chart shows probability values for up to 8S tests for dice pools from 1d6 to 16d6. Rules Module designers should develop an understanding of the relationship between test difficulty and pool size.

 There are a variety of online tools available to explore probability distributions that result from different sized dice pools and different success targets.

 

One free tool available online is the AnyDice Probability Calculator. It allows for complex simulations of dice rolls and calculation of probabilities. The following AnyDice function executes a Test and outputs the success probability.

function: test DICEPOOL:n against SUCCESSTARGET:n {
   result: DICEPOOL d (d6 >= 5) >= SUCCESSTARGET
}

\ Test a Dice Pool of 8 against a Success Target of 3: \
output [test 8 against 3]

The result of the above command will be to list out two percentages for the roll: 0: 46.82% which represents the probability of failure, and 1: 53.18% which represents the probability of success.

Action Dice & Exhaustion as a Limitation

Many ttRPG rule systems utilize specific mechanisms like slots and points to limit and balance character features and abilities. Expansion designers are encouraged to avoid inventing new mechanisms to limit character features and instead utilize existing mechanics.

Exhaustion (EX-binding of AD) is one of these fundamental mechanics that is specifically designed to limit actions for balance, and utilizing its rules for new abilities means that those abilities will compose seamlessly with existing core mechanics for exhaustion and recovery without any extra work.

For examples of how EX-binding may be applied as a limiting factor for character features, take the spellcasting abilities of the Spellweaver and the Lifecaller archetypes from the Spellweavers sample expansion.

These two capabilities apply EX-binding in different ways, but both approaches scale with feature complexity and compose with each other and with other system rules in a way that is natural and easy to understand for players and GMs alike.

Abilities vs Skills

When considering whether a new capability is best represented in your expansion as an Ability or a Skill, the main distinction is whether or not the capability can be learned, and therefore attempted without dice allocation. A capability which may be learned by training, observation, or trial and error—one that may be developed over time from nothing to expertise—is a Skill.

A capability that is inherent to an actor—whether intrinsic or extrinsic—is an Ability.