Purenrupu 砂紋
Purenrupu, also known as Simple Loop, is played on a square grid with some of its cells shaded as stones. Draw a single closed loop that passes through the centre of every unshaded cell exactly once, travelling only up, down, left and right. The loop turns at right angles, never crosses or touches itself, and never enters a stone. The puzzle is finished when one unbroken loop covers every open cell on the board.
Three modes: Classic gives you nothing but the shading, so the shape of the stones is the whole puzzle; Waystone numbers some of those stones, each number counting how many of that stone's four sides the loop runs straight past instead of turning against, which lets the board carry far fewer stones; Pinwheel promises that the finished loop is unchanged by a half turn of the board, so every line you work out hands you its opposite for nothing.
NazoKiro draws and generates its puzzles in the browser, so JavaScript has to be enabled to play. Nothing about you is sent anywhere either way.
All NazoKiro puzzles