Four Colour Map

Overview

Four Colour Map gives you an outlined collection of regions and four colours. Some regions are already coloured, and the rest must be filled so that regions sharing an edge have different colours. Meeting at a single corner does not make two regions neighbours. The puzzle therefore depends on the adjacency structure rather than on the visual size of a region. A large winding area may constrain several distant-looking patches at once. The supplied Map engine creates puzzles with a colouring consistent with the given regions, turning the familiar four-colour idea into a deduction exercise. You copy colours between regions instead of choosing them from a paint palette, and you can keep small candidate marks while working through ambiguous areas.

How to Play

Drag from an already coloured region into a blank region to copy its colour. Starting a drag outside the grid and ending inside a region removes an entered colour. Given colours cannot be changed. A secondary drag adds or removes candidate colour dots rather than committing a full fill; use the Secondary toggle for that action on a phone. Inspect the full boundary of an irregular region before choosing its colour. Complete every blank area without equal colours across a shared edge, using Undo whenever a drag reaches the wrong region.

Tips & Strategy

Look for an uncoloured region touching three different fixed colours: only the fourth colour remains possible. Follow narrow extensions of a region carefully, since they can create adjacency far from its centre. Two touching regions with the same two remaining candidates may jointly rule those colours out of a common neighbour. Candidate dots are particularly helpful on a complicated map, but avoid adding all four colours everywhere without a reason. When checking a suspected conflict, distinguish a shared edge from a corner contact; treating corner-touching regions as neighbours adds a restriction the game does not require.

About this version

Four Colour Map uses the locally compiled map engine from Simon Tatham’s Portable Puzzle Collection. The original authors retain credit under the MIT license. SonoTap provides the browser adaptation and this guide.