Knowledge base
How do I…?
The questions a slot developer actually asks — answered with pixi-reels. Searchable, and growing. 329 of 329 answered so far.
Getting started
Put a board on the screen and make it move.
- How do I create a reel set and show it on screen?
- How do I set how many reels (columns) the game has?
- How do I set how many rows are visible?
- How do I set the pixel size of a single symbol cell?
- How do I add a gap between reels and between rows?
- How do I put specific symbols on the board at startup?
- How do I register the list of symbol ids my game uses?
- How do I show a static board with no spinning at all?
- How do I attach the reel set to my existing PixiJS app?
- How do I center the reels inside the game canvas?
- How do I scale the whole board to fit different screen sizes?
- How do I change the symbols after the board is already built?
- How do I drive the reels from my own game loop / ticker?
- How do I clean up and destroy the reel set when leaving the screen?
Symbols
Define what lives in a cell and how it looks.
- How do I add a brand-new symbol type to the game?
- How do I make a symbol from a single texture/sprite?
- How do I make a symbol from a sprite-sheet animation?
- How do I make a symbol from a Spine skeleton?
- How do I render nothing for an empty cell?
- How do I set how often each symbol appears (weights)?
- How do I make one symbol much rarer than the rest?
- How do I anchor a symbol at the cell center vs the top-left?
- How do I resize a symbol whenever the cell size changes?
- How do I swap a symbol to a blurred texture while spinning?
- How do I attach custom data (a value, a tier) to a symbol instance?
- How do I read which symbol is currently shown in a given cell?
- How do I let a symbol's art overflow its cell without clipping?
- How do I give two different ids the same artwork?
- How do I tint or recolor a symbol per spin (e.g. a charged state)?
Spinning, speed & stopping
Start, stop, turbo, slam, and hold reels.
- How do I start a spin?
- How do I stop the reels on a result?
- How do I know when a spin has completely finished?
- How do I stagger reel starts so they begin one after another?
- How do I make the reels stop left to right?
- How do I add a turbo / fast-spin mode?
- How do I slam-stop the reels on a second button press?
- How do I boost only the current spin without changing the speed profile?
- How do I control the bounce/overshoot when a reel lands?
- How do I hold some reels still while the others spin?
- How do I respin just one reel?
- How do I abort a spin that is already in flight?
- How do I block a new spin until all animations finish?
- How do I add a timeout/watchdog if the server never sends a result?
- How do I keep the reels animating correctly on a hidden/background tab?
Results & forcing outcomes
Tell the reels exactly what to land on.
- How do I tell the reels exactly what grid to land on?
- How do I force a specific outcome for a demo or trailer?
- How do I read the final visible grid after a spin?
- How do I apply a result that came from my server?
- How do I land a symbol just above the visible window (in the buffer)?
- How do I land a tall symbol partially off-screen so only its edge shows?
- How do I use a seeded RNG so a spin is exactly reproducible?
- How do I guarantee at least one specific symbol lands this spin?
- How do I land a different row count on each reel in one result?
- How do I send a structured result that survives JSON / postMessage?
- How do I keep the visual result separate from the payout math?
- How do I replay the exact same spin again for a bug report?
Reel motion & board shape
Drop-in, roll-up, fall delays, and growing boards.
- How do I make symbols drop in from above instead of scrolling?
- How do I make a reel land with a bounce?
- How do I stagger the fall of individual symbols into place?
- How do I make symbols rise up from below (roll-up)?
- How do I spin one reel up and another down (mixed directions)?
- How do I peek the next symbol from above before it lands?
- How do I nudge a reel by one position after it stopped?
- How do I add rows to a reel at runtime (the board grows)?
- How do I add a whole new reel mid-feature (Infinity-Reels style)?
- How do I make reels horizontal instead of vertical?
- How do I fit two half-symbols in one cell (split symbols)?
- How do I keep a tall block intact while everything else scrolls?
Anticipation & near-miss
Build tension before the last reels land.
- How do I slow the last reel down when a big win is possible?
- How do I trigger anticipation only when 2 scatters are already in?
- How do I fake a near-miss with a scatter just above the line?
- How do I play a teaser sound/glow on the anticipating reel?
- How do I extend the spin time on specific reels for tension?
- How do I show an "almost" frame where the symbol overshoots then settles?
- How do I anticipate the final cell when one more coin means the grand?
- How do I chain anticipation across multiple reels (rolling tension)?
- How do I cancel anticipation cleanly if the tease misses?
- How do I make the anticipation reel speed up briefly before slowing?
- How do I run built-in anticipation on a single cell, the way the engine does it for a whole reel?
Win presentation
Lines, ways, clusters, highlights and big-win tiers.
- How do I highlight the winning symbols and dim the rest?
- How do I draw a payline across the winning cells?
- How do I play each symbol's own win animation?
- How do I show winning cells for a ways-to-win game (no lines)?
- How do I cycle through multiple winning lines one at a time?
- How do I draw connection lines between a connected cluster?
- How do I evaluate pays both ways (left-to-right and right-to-left)?
- How do I show a small/medium/big/mega win celebration by tier?
- How do I count the win amount up with a rolling number?
- How do I zoom and scale the board into a big-win banner?
- How do I skip the win presentation when the player taps?
- How do I keep the win highlight in sync with the win sound?
Cascades & tumbling
Remove winners, drop new symbols, repeat.
- How do I remove the winning symbols and drop new ones in?
- How do I run a tumble sequence until there are no more wins?
- How do I play a destroy/pop animation on cleared symbols?
- How do I make survivors fall down into the gaps?
- How do I control the fall delay between columns?
- How do I increment a multiplier on each cascade step?
- How do I keep a cluster-pays board (8+ connected) tumbling?
- How do I drop multiplier orbs that sum up at the end of the tumble?
- How do I spin once and then cascade (spin-then-tumble)?
- How do I let a special symbol survive the cascade and stick?
- How do I show the win presenter between cascade steps?
- How do I slam through all remaining cascades on a tap?
- How do I order the refills (which column fills first)?
Wilds
Sticky, expanding, walking, multiplier, generated.
- How do I make a wild stay stuck across the next spins?
- How do I make a wild expand to fill its whole reel?
- How do I make a wild walk one reel left each respin?
- How do I put a multiplier number on a wild?
- How do I randomly drop wilds onto the board before the spin?
- How do I expand a single special symbol to a full reel in free spins (Book style)?
- How do I keep a sticky wild for a fixed number of spins then drop it?
- How do I stack multiplier wilds so their values multiply together?
- How do I spawn a wild from a winning combo (chain-reaction wild)?
- How do I make a walking wild leave a multiplier trail behind it?
- How do I animate a wild crawling across reels along a path?
- How do I turn a whole reel wild for the duration of a feature?
Sticky cells & pins
Lock a cell to an id and keep it across spins.
- How do I lock a single cell to a symbol so it survives spins?
- How do I unlock a pinned cell again?
- How do I pin a cell for only N spins (a TTL)?
- How do I store a value/payload on a pinned cell?
- How do I read all currently pinned cells?
- How do I move a pin from one cell to another with animation?
- How do I keep a pin in place when the board reshapes (MultiWays)?
- How do I make a pin migrate back to its origin row when there is room?
- How do I override the spin result so pinned cells always win out?
- How do I animate a pin landing differently from a normal symbol?
Big / colossal symbols
One symbol that occupies an N×M block.
- How do I place a 2×2 symbol on the board?
- How do I make a 3×3 colossal symbol overlay the grid?
- How do I make a 1×3 tall bar symbol?
- How do I stop a big symbol from being placed by random fill?
- How do I land a tall block with only its bottom cell visible?
- How do I scale the big symbol's art to fill its whole block?
- How do I hold a big symbol while the rest of the board respins?
- How do I tumble a big symbol down through the cascade intact?
- How do I split a big symbol into single symbols on a win?
- How do I read the bounds of a big symbol block for an overlay?
- How do I clip a big symbol that lands past the top or bottom edge?
MultiWays & Megaways
Variable row counts per reel, per spin.
- How do I let each reel land a different number of rows?
- How do I set a min and max row count per reel?
- How do I compute and show the current ways count?
- How do I animate a reel growing from 2 to 7 rows mid-spin?
- How do I keep symbol size consistent as the row count changes?
- How do I run a cascade on a MultiWays board?
- How do I add a top horizontal reel (4-row extra strip)?
- How do I keep a pyramid (fixed jagged shape) instead of random rows?
- How do I anticipate on a tall reel that is about to grow?
- How do I combine MultiWays with big symbols safely?
Hold & Win
Lock-and-respin: the coin mechanic everyone ships.
- How do I build a Hold & Win board where each cell spins on its own?
- How do I lock a coin in place when it lands?
- How do I respin only the empty cells?
- How do I reset the respin counter to 3 on every new coin?
- How do I decrement the respin counter on a dry spin?
- How do I end the feature when the board is full (grand jackpot)?
- How do I carry the triggering coins into the feature already locked?
- How do I show the held count and respins left in a HUD?
- How do I make most spins land blank so coins flash by rarely?
- How do I drive the whole feature from server-decided hits per round?
- How do I do a column-respin variant (hold whole columns)?
- How do I switch from base game into the Hold & Win board cleanly?
- How do I play a slick reset back to the opening state after the feature?
- How do I gate the next respin until all land animations have settled?
- How do I award a mini jackpot when a whole row of coins fills?
- How do I grow the board by a row when a trigger condition is met mid-feature?
- How do I make a special coin upgrade all adjacent coins when it lands?
- How do I persist the locked board if the player reloads mid-feature?
- How do I run several Hold & Win boards at different bet tiers from one builder?
- How do I drive each Hold & Win cell as its own reel — start it, stop it, and read the symbol inside it independently?
- How do I make a single skip fast-forward every spin, flight and collect at once, then fire one "feature done" event?
Coins, values, collectors & jackpots
Money coins, mystery reveals, collectors, tiers.
- How do I print a money value on a coin?
- How do I format the value as 0.00 with a bitmap gold font?
- How do I scale the number to fit the coin face?
- How do I attach the value as data without baking it into the id?
- My coin is a mystery — how do I spin values inside it to reveal the number it held?
- How do I land a coin wearing a MINI/MAJOR word and reveal it into a money face?
- How do I show MINI/MINOR/MAJOR/GRAND jackpot plaques above the reels?
- How do I flash the matching jackpot plaque when its coin locks?
- How do I sum every coin value at the end and count it up?
- How do I make a collector coin pull every other coin's value into itself?
- How do I fly a value clone from each coin into the collector over an arc?
- How do I tick the collector total up as each value lands on it?
- How do I make a payer coin add its value to every other coin?
- How do I make a coin double or boost every value already on the board?
- How do I make a row/column of cells all act as collectors that sweep the board?
- How do I upgrade a coin's value tier in place (5 → 10 → 25)?
- How do I send collected coins flying to a feature meter above the reels?
- How do I send a golden trail to the meter instead of a flying coin?
- How do I show a coin counting up its own value before locking?
- How do I make a blank coin reveal a random value with a spinning reel inside it?
- How do I order the collect flights by row, by column, or all at once?
- How do I curve the collect flight toward the screen edge or center?
- How do I aim collect flights at a specific feature meter with a custom path?
- How do I attach a value overlay (100x, a jackpot label) that survives an in-place symbol swap and rides along when the symbol flies?
Symbol animations
Win, land, destroy, transform, idle, react.
- How do I play a win animation on a single symbol?
- How do I play an idle/breathing loop while a symbol sits?
- How do I play a landing animation when a symbol settles?
- A symbol gets destroyed by an object — how do I play its destroy animation?
- How do I morph one symbol into a different (higher) one mid-round?
- How do I reveal a mystery symbol into a matching symbol across the board?
- How do I freeze a Spine animation on its final frame and hold it?
- How do I play an arbitrary named Spine animation on a symbol?
- How do I await a one-shot animation and continue when it finishes?
- How do I play a different destroy animation per symbol art (shatter vs disintegrate)?
- How do I abort a destroy animation mid-tween when the player slams?
- How do I make a symbol react to a neighbour (e.g. shake when hit)?
- How do I charge a symbol up over several wins before it activates?
- How do I keep GSAP tweens in sync with the Pixi ticker?
Characters & objects over the reels
A creature above the reels that collects, throws, walks, reacts.
- How do I place a character above the reels that stays put?
- How do I throw a coin symbol at a character (a pig) above the reels?
- How do I make the character react (chomp, bounce) when a coin hits it?
- How do I make a fisherman collect every money-fish on the board?
- How do I fly each collected symbol's value into the character's pouch and total it?
- How do I walk a character across the reels stopping on each cell?
- How do I make a hammer/object smash specific cells and clear them?
- How do I have a special symbol shoot/affect another cell (sniper style)?
- How do I make persistent feature symbols interact across the board (Money-Train style)?
- How do I aim a flight at a moving target (the character animates while a coin flies)?
- How do I sequence many throws so they arrive one after another?
- How do I have the character grow/level up as it eats more coins?
Scatters & bonus triggers
Detect the trigger and enter the feature.
- How do I make a scatter pay regardless of its position?
- How do I count how many scatters are anywhere on the board?
- How do I require 6+ coins to trigger Hold & Win?
- How do I make a symbol that is both a coin and a bonus trigger?
- How do I show a partial-trigger teaser (5 in, need 6)?
- How do I show the scatters collecting into a trigger counter?
- How do I play a "bonus triggered" celebration before the mode swap?
- How do I award scatter pays and trigger free spins from the same scatters?
- How do I trigger different bonuses from different scatter sets?
- How do I scale the number of free spins by the scatter count?
Free spins & feature modes
Trigger, count, retrigger, swap modes, persist state.
- How do I trigger free spins from 3 scatters?
- How do I swap to a different reel set / background for the feature?
- How do I count down the remaining free spins?
- How do I retrigger and add more free spins mid-feature?
- How do I keep sticky wilds/multipliers persistent across all free spins?
- How do I pick a single expanding symbol at the start of the feature?
- How do I run a different weight table during the feature?
- How do I show a "feature complete, you won X" summary screen?
- How do I carry a running multiplier meter through the whole feature?
- How do I return to base game and restore the pre-feature state?
- How do I offer a buy-feature entry straight into the bonus?
- How do I gamble/upgrade the number of free spins before they start?
Bonus mini-games
Wheels, picks, ladders and gamble.
- How do I run a pick-a-prize bonus on clickable cells?
- How do I reveal hidden prizes one tap at a time?
- How do I spin a bonus wheel and land it on a segment?
- How do I settle the wheel pointer with a believable bounce?
- How do I offer a gamble / double-up on a win?
- How do I climb a prize ladder with collect-or-gamble choices?
- How do I run a "pick until you hit 3 of a kind" collection bonus?
- How do I award a random multiplier from a chest or orb?
- How do I run a trail / board-game bonus that hops across cells?
- How do I tally "you collected X" at the end of the pick?
Meters, multipliers & progression
Accumulators, level-ups, progressive jackpots.
- How do I show a multiplier meter above the reels?
- How do I increment the meter on each win and reset on a miss?
- How do I level up a jar/symbol multiplier each time it wins?
- How do I fill a progress bar that unlocks a feature at 100%?
- How do I animate a value flying into the meter and bumping it up?
- How do I drive a progressive jackpot value that ticks up live?
- How do I show a coin-collect counter that aggregates bonus coins?
- How do I apply the meter's multiplier to the final win?
- How do I keep the meter and its server value from drifting apart?
- How do I sticky-stack position-locked multipliers that persist?
Sound & juice
Hook sound and haptics to game events.
- How do I play a sound when a reel stops?
- How do I play a per-coin sound as each one lands in stagger order?
- How do I rise the anticipation music as tension builds?
- How do I duck the music during a big-win count-up?
- How do I pitch the count-up sound higher the longer it runs?
- How do I layer base vs feature music and crossfade between them?
- How do I fire haptics/vibration on a jackpot hit?
- How do I sync a sound exactly to a Spine animation event?
- How do I cut all feature sounds cleanly when the player exits?
- How do I keep audio aligned when the player slams the reels?
HUD, buttons & overlays
Spin button, bet, autoplay, counters, tooltips.
- How do I wire a single spin button that also slam-stops?
- How do I disable the spin button while a spin is running?
- How do I show the current bet and balance?
- How do I run autoplay for N spins with a stop condition?
- How do I overlay a HUD that reads purely from board events?
- How do I draw a value label centered on a specific cell?
- How do I position an overlay using a cell's exact pixel bounds?
- How do I add clickable hit-areas per cell (pick-a-cell bonus)?
- How do I keep HUD text crisp at any board scale?
- How do I show a "respins left" badge that updates live?
- How do I render the board on a dark feature background vs a light base?
Bet, lines & paytable
Lines vs ways, bet levels, the paytable screen.
- How do I switch a game between paylines and ways-to-win?
- How do I let the player change the bet level?
- How do I scale coin values by the current bet?
- How do I show a paytable screen for the registered symbols?
- How do I draw and highlight which lines are active?
- How do I recompute the ways count when the board shape changes?
- How do I price the buy-feature off the current bet?
- How do I lock the bet during a feature?
Layout, orientation & transitions
Responsive boards, portrait/landscape, intros and wipes.
- How do I lay the board out for portrait vs landscape?
- How do I scale the board to fit a fixed safe-area?
- How do I reflow the HUD when the orientation changes?
- How do I keep the board centered with jackpot panels flanking it?
- How do I anchor a top feature meter relative to the reels?
- How do I play an intro that assembles the reels on load?
- How do I transition between base and feature with a wipe?
- How do I play an outro that breaks the board apart on exit?
- How do I support an ultrawide background behind a fixed board?
- How do I mirror the layout for RTL locales?
Performance & lifecycle
Pooling, disposal, memory, big grids.
- How do I recycle symbols instead of recreating them every spin?
- How do I cap how many instances of a symbol are pooled?
- How do I dispose everything without leaking textures or tickers?
- How do I keep a 7×7 board with many masks from dropping frames?
- How do I share one mask across many cells?
- How do I avoid stutter on a long session of continuous spins?
- How do I tear down a feature's 20+ sub-reelsets safely?
- How do I keep tweens from leaking when a symbol is recycled mid-animation?
- How do I batch Spine instances so the GPU does not choke?
- How do I preload feature assets so the mode swap has no hitch?
Debugging & testing
See the opaque canvas, make spins deterministic.
- How do I dump the current board state as readable JSON?
- How do I print an ASCII grid of the visible symbols?
- How do I log every domain event as it fires?
- How do I diagnose a stuck spin that never lands?
- How do I force a guaranteed jackpot for a screenshot?
- How do I make a deterministic spin in a unit test?
- How do I run the engine headless with no canvas for tests?
- How do I add a cheat panel (force a symbol, force a hit)?
- How do I record and replay a spin frame by frame?
- How do I assert the visible grid matches the expected result?
Server, math & integration
Wire the engine to an RGS and recover state.
- How do I drive every spin from a server (RGS) response?
- How do I keep all payout math on the server and only present results?
- How do I show a spin while waiting for the server, then snap to its result?
- How do I recover an interrupted feature on reload (resume state)?
- How do I format currency values for different locales?
- How do I map a server symbol-id scheme onto my registered ids?
- How do I sequence multi-step server features (round → round → collect)?
- How do I keep visuals honest when the server is the only source of truth?
- How do I handle a desync between the animation and the server state?
- How do I satisfy regulatory replay (exact reproduction of any past spin)?