Picture Maze

Solve the maze and the single winding path from entrance to exit shades a hidden picture — a heart, star, diamond, or cross.

What it is

A maze with one entrance and one exit. There is exactly one route between them, and the cells that route passes through are exactly the cells of a hidden silhouette. Colour the corridor you travelled and the picture appears.

How to play

Solve it as an ordinary maze — but the goal is the drawing, not just the exit. Every dead-end branch leads out of the shape, so a route that strays off the silhouette is heading down a false corridor.

Purpose

The maze lane’s most rewarding format, and one that ties the two ends of the workspace together: the silhouettes come from the same parametric-shape idea lako-dottodot verifies, and the corridors from lako-maze, with the picture riding the solution instead of the dots.

History

Picture mazes (Conceptis’s Maze-a-Pix among them) turned the plain maze into a colouring reveal, and have been a newspaper and puzzle-book fixture since the 2000s.

This implementation

• Spec knobs: size (10–20), picture (heart / star / diamond / cross; empty picks one per seed), cell, line.
• Generation, turned inside out: rather than carve a maze and hope its solution traces a shape, the construction makes the shape’s path the solution. A long simple path is found within the silhouette (Warnsdorff- guided search from boundary starts), then every remaining cell is hung off it as a dead-end branch, growing a spanning tree of the whole grid.
• Guarantees: because the finished maze is a tree, the entrance-to-exit route is unique — checked by an independent path count, not assumed — and it is the silhouette path by construction. The solution never strays outside the shape, and coverage (reported in the metadata) is high enough that the picture always reads; a grid graph is bipartite, so a few silhouettes admit no fully-covering path, and the search takes the longest one rather than refusing the picture. Rated by solution length over grid size.