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.skip().

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.

SpinController — The brain of a spin. Drives every reel through its lifecycle phases, coordinates setResult(), and emits events.

ReelPhase — A single stage in a reel’s life during a spin. pixi-reels ships four: StartPhase (wind-up), SpinPhase (constant-speed blur), AnticipationPhase (optional suspense slow-down), StopPhase (decelerate, snap, bounce). Add your own via PhaseFactory.

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).

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.

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.