The lead-in is the gap between the player clicking SPIN and the reels visibly starting to fall. It’s not a library feature. just an await new Promise((r) => setTimeout(r, ms)) before reelSet.spin() in your handler. But it dramatically changes the slot’s perceived pace, and pairing the right lead-in with your spin SFX is the difference between a satisfying click and a button that “doesn’t feel like it did anything.”
Every canvas below runs the same scripted spin + destruction. Only the LEAD_IN_MS constant at the top of each recipe changes.
0 ms. instant
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const LEAD_IN_MS = 0;
onSpin: async () => {
if (LEAD_IN_MS > 0) await new Promise((r) => setTimeout(r, LEAD_IN_MS));
reelSet.setDropOrder('ltr');
const spinDone = reelSet.spin();
// ...
}The fall starts the same frame the click handler runs. Snappiest possible feel; perfect for high-velocity play where the player taps-spins many rounds per minute. Pair with a sound that triggers WITH the fall, not before. a lead-in sound followed by an instant visual reads as mistimed.
150 ms. subtle
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const LEAD_IN_MS = 150;Just enough room for a short “tap” SFX to play before the reels move. The pause is below the threshold where players think “why isn’t anything happening?”. still feels responsive, but you’ve earned a beat for sound design.
350 ms. anticipation
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const LEAD_IN_MS = 350;A clearly perceived deliberate pause. Room for a full “spin-up” SFX, a button-press animation, or a “READY” tone. Common in mid-tier slots where the spin is the main event, not a transactional micro-action.
700 ms. suspense
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const LEAD_IN_MS = 700;Dramatic. The reels stand still while music swells, a “GO!” stinger fires, or a feature-pick UI flashes. Use sparingly. fine for bonus / free-spin / jackpot reveals, exhausting on every base-game spin. Players will skip this if you don’t give them an UNSKIPPABLE reason to wait.
Picking the lead-in
| Lead-in | Use for | Avoid for |
|---|---|---|
| 0 ms (instant) | Turbo modes, fast-paced reskins | Slots that lean on sound design |
| 150 ms (subtle) | Default base game on most modern slots | Bonus rounds that need narrative beats |
| 350 ms (anticipation) | Mid-tier base game, story-driven themes | Turbo or high-volume play modes |
| 700 ms (suspense) | Feature reveals, free-spin triggers, jackpot intro | Base-game spins (player fatigue) |
A common pattern: scale the lead-in by speed mode. In 'normal' speed use 200-350 ms; in 'turbo' drop to 50-100 ms; in 'superTurbo' go to 0. Same handler, different LEAD_IN_MS selected from reelSet.speed.activeName.
Cascade refills don’t get a lead-in
Worth flagging: the lead-in only applies to the player’s spin() click. Cascade refills (Moment B. reelSet.refill(...)) chain off the previous win-destruction and shouldn’t pause again. If you add await wait(LEAD_IN_MS) in the cascade loop too, you stack pauses on every cascade level and the round drags. The lead-in is exclusively before the first spin() of a round.
Related
- Tumble feels. varies the animation easing & duration; pairs with any lead-in.
- Cascade refill orders. varies the post-win drop pattern.
- Cascade 6×5 tumble. full cluster + multiplier example.