Inaba-Style Math Puzzles
Three hand-made puzzles in the Japanese tradition.
Area Maze. Each room shows its area. Start at the S room and tap neighbouring rooms to walk to the G room. Never reuse a room. The areas of all rooms you pass through (including S and G) must total exactly 20. Tap your last room to step back.
Shikaku. Divide the grid into rectangles. Each rectangle must contain exactly one number, equal to its area, and every cell must be covered. Drag to draw; tap a rectangle to erase it.
KenKen. Fill the 4×4 grid with 1–4 so no digit repeats in any row or column. Each bold-outlined cage must produce its target using the given operation (for − and ÷, subtract or divide the larger by the smaller).
Zukei (Slant). Tap a cell to cycle through /, \ and blank. Every circled number tells how many diagonal lines touch that dot. The lines must never form a closed loop, and every cell needs a diagonal. Satisfied numbers turn green.
Kurodoko. Tap cells to shade them black. Shaded cells may never touch each other by an edge, and all unshaded cells must stay connected. A number cell stays unshaded, and its number counts the unshaded cells you can see from it in a straight line along its row and column (including itself) until you hit a black cell or the edge.
Kakuro. Fill the white cells with digits 1–9. The number in a grey cell is the sum of the run of cells to its right (top-right figure) or below it (bottom-left figure). No digit may repeat within a run.
Kin-Kon-Kan (mirror puzzle). Tap cells to place a mirror / or \ (tap again to cycle, then blank). The numbers beside the grid say how many mirrors each row and column holds. A beam enters at IN on the left of the top row and must leave through OUT. The beam is drawn live as you place mirrors.
Hitori. Shade cells black so that no number appears twice in any row or column among the unshaded cells. Shaded cells may never touch by an edge, and all unshaded cells must stay connected.
Futoshiki. Fill the 4×4 grid with 1–4 so no digit repeats in a row or column. The signs between cells show which neighbour is larger (< and > point to the smaller one; ∧ means the upper cell is smaller, ∨ means it is larger). Some digits are given.
Nurikabe. Tap cells to turn them into black “sea”. The unshaded cells form islands. Each island contains exactly one number, which is its size in cells. All the sea must be one connected piece, and there may be no 2×2 block of sea.
Magic Square. Place the digits 1–9, each used once, so every row, every column and both long diagonals add up to 15. Orange digits are given.