Kuromasu

Overview

Kuromasu describes a landscape through the distance visible from numbered squares. You shade some unnumbered cells black, and each clue must see exactly its stated number of white cells along the four orthogonal directions, counting itself once. A black cell blocks the view; another numbered white cell does not. Two black cells cannot share an edge, and all white cells must remain connected. These global restrictions prevent a collection of locally correct but disconnected sight lines from passing as a solution. The hosted Range engine generates puzzles with different sizes and difficulty settings. Because the board stays still while you reason, you can compare the longest possible view with the shortest forced view before deciding where a blocking square belongs.

How to Play

Click an unnumbered cell to shade it black. Secondary input places a white dot, recording that the cell must remain open. On a phone, enable Secondary when marking confirmed white cells. Count the clue square itself only once, then add the visible white cells above, below, left and right until a black cell or border stops each ray. Complete all clue counts while preserving the connected white area. Undo reverses a choice; Restart returns to the same initial clues.

Tips & Strategy

A low clue near a corner often forces nearby blockers because the border already limits two directions. High clues can force long runs of white cells before you know where their final blockers go. Every black cell immediately forces its orthogonal neighbours white, which can extend another clue's minimum visibility. Check narrow connections between large white areas before shading a cell there. If it is their only bridge, blackening it would split the white region. Avoid treating numbered cells as walls: light of sight passes through them, so two aligned clues can constrain one another over a considerable distance.

About this version

Kuromasu uses the locally compiled range 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.