Sticky wilds

Mechanic rules

• When a wild lands, remember its cell and a countdown (3 spins).
• On subsequent spins, replace the natural symbol at that cell with a wild until the countdown hits 0.
• Each new wild resets the countdown on its cell.

Setup

1. Track stickies

type Sticky = { reel: number; row: number; spinsLeft: number };
const stickies: Sticky[] = [];

2. Rewrite the grid before every spin

Use the library’s setHeld() + holdAndWinProgress pattern, or feed your own grid:

reelSet.events.on('spin:complete', ({ symbols }) => {
  for (const s of stickies) s.spinsLeft--;
  for (let r = 0; r < symbols.length; r++) {
    for (let row = 0; row < symbols[r].length; row++) {
      if (symbols[r][row] === 'wild') {
        const existing = stickies.find((x) => x.reel === r && x.row === row);
        if (existing) existing.spinsLeft = 3;
        else stickies.push({ reel: r, row, spinsLeft: 3 });
      }
    }
  }
  stickies.splice(0, stickies.length, ...stickies.filter((s) => s.spinsLeft > 0));
});

3. On next spin, force those cells to wilds

engine.setHeld(
  stickies.filter((s) => s.spinsLeft > 0).map((s) => ({ reel: s.reel, row: s.row, symbolId: 'wild' })),
);

4. Cheat: guaranteed sticky

forceCell(reelIndex, rowIndex, 'wild') lands a fresh wild in the same spot every spin — perfect for reviewing the sticky animation on loop.