Glossary

Alphabetical, by the way the term shows up in Verse Builder UI or generated Verse — not by abstract definition. Each entry links to the page that explains the concept in depth.

@editable

Verse keyword that exposes a class property to the UEFN editor. Designers can wire actors or change numbers in the Details panel without touching code. Configs and device bindings both compile to @editable. See Devices & @editable.

Action

The DO part of a rule. Side effects: grant items, change variables, show HUD, teleport. Actions in a single rule run top-to-bottom. See Actions atom library.

Agent

The Verse type that represents whoever caused an event — usually a player. Most events pass the agent implicitly to the rule's IF and DO blocks.

Atom

A single piece in the rule editor. Events (WHEN), Conditions (IF), and Actions (DO) are all atoms. Each has a unique atomId and a typed set of parameters.

Binding

A typed reference from a Consumer device to a Provider device, declared in the Module tab. Compiled to @editable on the Consumer; wired in UEFN by dragging the Provider actor in. See Multi-device.

Composer

The pure-functional pipeline that turns a list of rules into Verse code. Same inputs always produce the same output — no randomness, no side effects.

Condition

The IF part of a rule. Optional gate that re-evaluates every time the WHEN event fires. Multiple conditions combine with AND (default) or OR. See Conditions atom library.

Config

A designer-tunable constant exposed via @editable. Read-only from rules. Used for balance, time constants, caps. See Game data: Config.

Consumer

A device that depends on a Provider — declares a Binding, consumes Exports. Multi-device packs are 1 Provider + N Consumers.

Device

One file in your project. Compiles to a Verse class extending creative_device, placed in UEFN as an actor. Owns its rules, game data, and bindings.

Event

The WHEN part of a rule. The trigger — On Elimination, On Button Pressed, On Timer Elapsed. See Events atom library.

Export

A public method a Provider device exposes for Consumers to call. Declared in the Module tab. Compiled to <public> methods.

Game Data

The collective name for everything you declare alongside rules — Variables, Configs, Phases, Messages, Inventories, and the Module config. All live in the Game Data tab.

Inventory

A slot-based per-player container — backpack, hotbar, crafting grid. Persistent by default. See Game data: Inventories.

IR

The typed intermediate representation the Composer V2 pipeline uses. You don't interact with it directly — it sits between “rules” and “Verse code” and powers validation, dead-code elimination, and helper inlining.

Message

A named piece of player-facing text. Defined once, referenced from any HUD/popup action. Tokens like {coins} inject variable values at runtime. Compiled to <localizes> declarations.

Module

The multi-device configuration for one device — its role (Provider or Consumer), Exports, Bindings. See Game data: Module system.

Pack

A bundle of 2+ devices that work together — typically 1 Provider + N Consumers. Verse Builder ships several Pack presets (Tycoon, Economy Shop, …) you can load as starting points.

Persist

A per-player variable flag. When on, the value survives disconnects and rejoins via Fortnite's player-data system. When off, the value resets to the default every round.

Phase

A named stage of your game — lobby, game, ending. Exactly one phase is current at a time. Rules can be gated to specific phases. See Concepts: Phases.

Provider

A device that owns shared state and exposes public methods (Exports) for other devices (Consumers) to call. Exactly one Provider per pack.

Rule

The atomic unit of behavior: WHEN something happens, IF a condition is true, DO these actions. Devices contain ordered lists of rules.

Scope

A per-variable flag: player (each user has their own copy) or global (one shared value across the whole island).

Variable

A named value that can change at runtime — coins, level, current_zone. Configured with a Type, Scope, Default, and Persist flag. See Game data: Variables.