Glossary

Two groups of terms are mixed here: slot vocabulary (concepts every slot uses, regardless of library) and library-specific names (what pixi-reels calls its pieces). If a word feels jargon-y, it is probably defined here. search the page.

Slot vocabulary

Anticipation. A deliberate slow-down on a specific reel to build tension. Classic pattern: two scatters are already on screen, so the last couple of reels decelerate dramatically to make the player hope for a third.

Base game. The normal spin mode (as opposed to a bonus round like free spins or Hold & Win).

Bet. Amount staked per spin. Not modeled by pixi-reels. it is a number in your game code.

Bonus. Any secondary game mode triggered off the base game (free spins, Hold & Win, pick-a-prize, etc.).

Cascade (tumble). A chain mechanic: winning symbols disappear, remaining ones fall, gaps fill from above, re-check for wins, repeat. Candy Crush with a paytable.

Cluster win. Win shape where N+ adjacent matching symbols (orthogonally connected) pay, regardless of row or column. Compare with “line win”.

Free spins (FS). Bonus round where the player gets a fixed number of spins at no cost. Often includes sticky wilds, multipliers, or expanding wilds.

Grid. The two-dimensional snapshot of visible symbols, indexed grid[reelIndex][rowIndex]. A 5x3 slot has a 5x3 grid.

Hold & Win (Link & Win, Respin). Bonus round where special “coin” symbols lock in place when they land, and you keep respinning until no new ones land. or the whole grid fills and pays a jackpot.

Line win. Win paid for N+ matching symbols on a payline (usually left-to-right on a fixed row).

Multiplier. A number applied to a win. Often grows with consecutive cascades.

Near-miss. Result that almost triggered a big win (two scatters on screen, the third just off the visible window). A retention trick.

Paytable. The map from winning combinations to payouts. Lives on the server, not in this library.

Payline. A fixed path through the grid (row 1, zigzag, V-shape) where matching symbols pay.

Reel. One vertical column of symbols.

Reel strip. The (long, invisible) list of symbols a reel draws from. pixi-reels does not expose this directly. it just asks for a next symbol from a frame middleware chain.

Respin. A spin where some reels are held in place and only the others move. A single-reel respin holds every reel except one; a Hold & Win respin holds every “coin” cell.

RTP (Return To Player). Expected long-run payout percentage (e.g. 96%). Determined by the paytable and reel strips on the server.

Scatter. Symbol that pays regardless of position and usually triggers the bonus. Unlike line wins, scatters count no matter where they land.

Slam-stop (skip). The player presses the spin button a second time and the reels land immediately. In pixi-reels this is reelSet.skipSpin().

Spin. One turn of the reels. In this library, the lifecycle is START → SPIN → (ANTICIPATION) → STOP → IDLE.

Stacked symbol. A symbol that fills several rows of the same reel in a single column. Often wilds.

Sticky wild. A wild that, once it lands, stays in place for the remaining spins of a round.

Symbol. One cell on a reel. A graphic (sprite, animated sprite, Spine skeleton, or a custom drawing).

Turbo / Super-turbo. Faster spin profiles. Same outcome, less wait.

Walking wild. A wild that moves one column per respin and typically triggers free respins along the way.

Wild. Substitutes for other symbols to complete wins. Usually cannot substitute scatters.

Win spotlight. Visual highlight on winning cells. pixi-reels ships SymbolSpotlight.show() / .cycle() for this.

Library-specific names

ReelSet. The top-level object. Think of it as “the whole slot board”: a PixiJS container that holds the reels, the spin controller, the speed manager, and the spotlight. You build one with new ReelSetBuilder()...build() and addChild it to your stage.

ReelSetBuilder. A fluent builder (chainable methods) that turns a pile of config into a ReelSet. Use it so you cannot forget to wire a required piece. every mandatory call is enforced at .build() time.

Reel. One column. Owns the symbols currently on screen, their vertical motion, and the “land on this frame” logic.

ReelSymbol. Abstract base class for a single cell. Subclass it to draw whatever you like: SpriteSymbol for plain sprites, AnimatedSpriteSymbol for sprite sheets, SpineSymbol for Spine skeletons, or your own.

ReelViewport. The clipping and layering container. Holds the mask (so symbols that scroll above/below the visible area don’t leak) plus a “promoted” layer where winning symbols get lifted above the mask for a celebration animation.

Spin controller (internal). The brain of a spin. Drives every reel through its lifecycle phases, coordinates setResult(), and emits events. Wired by ReelSet. consumers never construct one. In 1.0 it is no longer exported from the package entry.

ReelPhase. A single stage in a reel’s life during a spin. pixi-reels ships built-in phases for wind-up, constant-speed blur, optional anticipation slow-down, and the decelerate-snap-bounce stop. Add your own by extending ReelPhase and registering via the PhaseFactory callback in builder.phases(f => f.register('name', MyPhase)). The built-in phase classes are internal; only the Config TYPES (StartPhaseConfig, SpinPhaseConfig, etc.) are exported as stable shape descriptions.

SpinningMode. The big strategy switch that decides what a spin even means. StandardMode is the default (each reel runs through the phases independently). CascadeMode replaces columns atomically for tumble mechanics. ImmediateMode is a no-motion mode for testing.

SpeedManager. Holds named SpeedProfile objects (timings, easings, bounce distance). Switch profiles at runtime with reelSet.setSpeed('turbo').

SymbolSpotlight. The win-animation primitive. Dims non-winners, promotes winners above the mask, runs playWin() on each, and can cycle through multiple lines.

FrameBuilder / middleware. A tiny middleware pipeline that decides what symbol identity goes into each buffer slot when a reel needs another row. Intercept it to implement “no three-in-a-row”, “inject a mystery symbol every 7 frames”, etc.

ObjectPool<T>. The reuse bucket behind every symbol. Scrolling a 5x3 reel for 5 seconds allocates zero new ReelSymbol objects. they come from and return to the pool.

EventEmitter. Typed pub/sub. Events are namespaced with colons (spin:start, spin:reelLanded, speed:changed). Every exit path from a spin fires an event. wire audio / HUD / analytics to events, not to method calls.

TickerRef. Safe wrapper around PIXI.Ticker. Tracks every callback it adds and removes them all on destroy. Never call ticker.add() directly in this codebase.

Disposable. Interface every resource-holding class implements. destroy() cascades through the composition tree so one reelSet.destroy() cleans the whole scene up.

enableDebug(reelSet). Attaches window.__PIXI_REELS_DEBUG with .log(), .snapshot(), .grid(), .trace(). the only way to inspect reel state through a canvas (including from an AI agent).

CellPin. The cell-persistence primitive. Lock a symbol id to a cell with reelSet.pin(col, row, id); the engine acquires an overlay during spin, migrates the cell on reshape, and supports an animated movePin(from, to) tween. Works with any ReelSymbol subclass. The pin primitive is general, not Spine-specific.

RefillOptions / RefillResult. The typed pair around reelSet.refill(opts). Pass { winners, grid, mode?, signal? }; receive { winnersRefilled, finalGrid, wasSkipped, duration }. Mirrors the shape of RunCascadeOptions / RunCascadeResult so the cascade-loop primitives compose cleanly.

RunCascadeOptions / RunCascadeResult. The pair around reelSet.runCascade(opts). The two required callbacks (detectWinners, nextGrid) encode game rules; the result reports chainLength, totalWinners, finalGrid, and wasSkipped. signal: AbortSignal lets the caller slam mid-chain.

createTestReelSet. The headless harness. Builds a ReelSet with a FakeTicker + HeadlessSymbol so you can run a full spin lifecycle in Node, with no DOM or canvas, and assert on the final grid. In 1.0 it ships at the pixi-reels/testing subpath so the harness drops out of production bundles.

CheatEngine (examples). Deterministic outcome generator used by demos and tests. Lives in examples/shared/, not in the library. ADR 009 covers why.

Changeset. A small markdown file under .changeset/ describing a release-worthy change and which package(s) to bump. Generated by pnpm changeset; consumed by the release workflow to version and publish.

Snapshot release. An ephemeral npm publish stamped <base>-<tag>-<timestamp> under a per-branch dist-tag. Every push to a non-main branch creates one, so reviewers can pnpm add pixi-reels@<branch-tag> and test.