---
title: "Deduction puzzles"
package: "@phaser-ae/deduce"
tier: Pro
version: 3.0.0-3
released: 2026-10-14
updated: 2026-10-20
description: "Three seeded logic puzzles, nonograms, light-toggling boards and colour floods, whose nonogram and toggle hints are exact deductions rather than guesses."
url: https://phaser.io/packs/deduce
site: Phaser - https://phaser.io
---

# Deduction puzzles

Three logic puzzles with seeded generators and hints you can trust: picture-logic nonograms, light-toggling boards
and colour floods. The nonogram and toggle hints are computed exactly, so a hint is never a guess.

## What it does

A **nonogram** is a picture hidden in a grid, with a run-length clue for each row and column. The pack solves a line
exactly, for any length, with a dynamic programme over its clue: it never lists arrangements and never marks a cell
that is not forced. The hint, `solveStep`, marks the forced cells of the first line that has any. The generator draws
random pictures and keeps the first that line logic alone can finish, and its `lineSolvable` flag tells you honestly
whether it found one, so a guess-free puzzle is something you can check rather than assume.

The **light-toggling puzzle**, in the style of Lights Out, toggles a cell and its neighbours on every press. Pressing
is addition in a two-value arithmetic, where twice is nothing and order does not matter, so Gaussian elimination
computes the exact set of presses that turns everything off. Every board the pack makes is solvable, because it is
scrambled from all off, and when there are several answers the hint returns one with the fewest presses.

The **colour flood**, in the style of Flood-It, grows a region from an origin cell as the player picks colours, until
it covers the board within a move limit. `preview` says exactly how many cells a colour would add now, and the hint is
the colour that absorbs the most. The default move limit is set from greedy play, so the board can always be won
within it.

## Features

- **Exact nonogram lines** — a dynamic programme over each clue finds the forced cells, in time proportional to cells
  times blocks.
- **Honest generation** — `lineSolvable` reports whether line logic alone finishes the picture.
- **Your own pictures** — pass a `solution` of booleans instead of generating one.
- **Clue checks** — `lineSatisfied` says when a row or column reads as its clue, to dim a finished clue.
- **Exact toggle solutions** — `solution()` gives the presses that clear the board, each cell at most once.
- **Fewest presses** — chosen among several answers, for every square cross board up to 20 by 20.
- **Toggle stamps** — a cross, a 3×3 square or your own offsets, with optional wrapping round the edges.
- **Flood previews and hints** — `preview` for any colour's exact gain, and `findMoves` ranks every colour.
- **Seeded and headless** — every board is deterministic from its seed and draws nothing itself.

## Good for

- **Picture-logic puzzle books**, nonograms in the style of Picross or Griddlers, with a hint that only marks what is
  certain.
- **Light-toggling puzzles**, in the style of Lights Out, including variants with square or custom stamps and
  wrapped boards.
- **Colour-flood puzzles** in the style of Flood-It or Color Flood, with a move limit and a greedy hint.
- **Daily puzzles and puzzle collections**, where a seed reproduces each board.
- **Teaching logic**, where a hint must be a deduction the player could have made.

## Make it yours

Each puzzle takes its own small config. Every board has a grid size and a seed. A nonogram adds a fill density for
its generator, or your own picture. A toggle board adds its stamp, whether it wraps, and how many random presses
scramble it. A flood adds the number of colours, a move limit and the cell it grows from.

Two different uses of the same pack: a fifteen-by-fifteen nonogram generated at a high density and checked with
`lineSolvable`, with `solveStep` behind a hint button; and a wrapped toggle board with a 3×3 stamp, where the hint
shows the exact presses that finish it. A flood on a fourteen-by-fourteen board with six colours, grown from a corner,
is a third game again.

## A quick look

A generated nonogram, checked, marked and hinted:

```ts
const pic = game.deduce.createNonogram({ cols: 15, rows: 15, seed: 4, density: 0.6 });
if (!pic.lineSolvable) { /* this picture needs guessing: try another seed or density */ }
drawClues(pic.rowClues, pic.colClues);
pic.set(2, 5, 'fill');                        // 'fill', 'cross' or 'unknown'
const hint = pic.solveStep();                 // one line's forced cells, now marked
if (pic.solved) win();
```

## Works with

- `reveal` — for hidden-cell deduction games where a hint must also be certain.
- `netflow` — for grids that light up through connections, such as pipe and network puzzles.

## Good to know

- A generated nonogram never needs the cross-referencing or guessing hard hand-made puzzles use, which caps its
  difficulty. Large or sparse boards often fail to be line-solvable within the generator's 40 tries; check the flag
  and try another seed or density.
- The nonogram hint treats the player's marks as known, so a wrong mark can mislead it.
- The flood has no optimal solver: its hint and its default limit both come from greedy play.
- None of the three has undo; keep your own list of moves, or rebuild a board from its seed.

---

## For AI agents: Phaser AE

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- **Phaser AE in the browser** (https://phaser.io/agent): the game's design, and a crew of bots that make its art, sprites, music, sound effects, logos, title screens, game UI, textures, shaders, 3D models and video, then build, test and publish the game. Every tool there is registered with Web MCP (`document.modelContext`, with `window.phaserDesk` for browsers without it), so an agent in the user's browser can call the tools directly once the user is signed in. Tools that make something spend the user's credits.
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Read any page of this site as Markdown by adding `.md` to its URL (the home page is https://phaser.io/index.md), or by asking for `text/markdown`. The index for agents is https://phaser.io/llms.txt. On the site's pages, the browser's Web MCP also offers `phaser_ae_guide`, `read_page_as_markdown` and `open_phaser_ae`.