How to Play Kakuro (Cross Sums)

Kakuro (also called Cross Sums) is a Japanese logic puzzle often described as a mathematical crossword. Every horizontal or vertical run of white cells must add up to the clue sitting at its start, and no digit may repeat inside a run. It looks a bit like Sudoku, but instead of placement rules you reason with sums and number combinations — e.g. a two-cell run of 17 can only be 8 + 9. GridPaw Kakuro is free, runs entirely in your browser, and adds two twists: 4 guided tutorial lessons and a paw-print fog mode (from the first Medium level) that hides part of the board until you've solved the visible block.

Your First Puzzle

1. Open the game. Go to gridpaw.com/kakuro. You start on Tutorial 1/4 — "Clues are sums", a tiny guided board. Solve it and the next lesson auto-loads (there is no win popup in the tutorials — just a checkmark message).
2. Select a white cell. Click or tap it — it gets an orange outline. The keypad below the board (1–9) now shows you which digits are legal in that cell: amber-ringed digits are OK, struck-through digits are already used elsewhere in the run, and digits on a pink background would push the run past its clue sum.
3. Fill the digit. Tap a key (or press 1–9 on your keyboard). Each cell belongs to two runs — one across and one down — and both must eventually hit their clue sums without repeats. Tap the 🗑-style ⌫ key (or Backspace / Delete / 0) to clear the selected cell.
4. Finish the board. The moment every white cell is filled correctly, the "Solved!" popup appears. The tutorial lessons teach you the clues; the four lessons cover: sums, no-repeats, extreme clues (17 = 8+9), and a bigger combined board.

Optional: during the tutorials you can press "Skip tutorial »" to jump straight into the campaign.

Every Button on the Screen

Hint: after placing a digit the selection automatically jumps to the next empty cell, so you can flow through the board without re-clicking.

Fog Mode: The GridPaw Twist

From the first Medium level (campaign level 4) the board is split into two blocks and the far block hides under a paw-print fog:

• Solve the visible block first. Once every run in the visible block sums correctly, the fog lifts ("Fog lifted!") and the far side is revealed. The blocks never share a run, so the reveal can never trap you — every fog board is verified to have exactly one solution.
• Tap the fog to peek. Each fog level gives you 2 free peeks: tapping a fogged cell reveals it (and the clue numbers of its runs). The peek bar below the board shows Free peeks left: N / 2.
• Out of peeks? A small popup offers more (a "Watch ad" option or "Cat coins" mode) — in the current demo build this is a mock-up and nothing is actually charged. Close it with ✕ and keep solving by logic.

There is no fog in the Easy levels, and the Hard boards use a denser wall layout instead of a bigger grid.

Levels, Progress & Daily Puzzles

The journey is: 4 tutorials → 11-level campaign → endless daily puzzles.

• The chip above the board says Tutorial 1/4 — <lesson>, then Level N/11 — Easy/Medium/Hard — S×S, and Daily once the campaign is done.
• Progress saves automatically in your browser (your current campaign level) — close the tab and come back later; you resume where you left off.
• Daily puzzles are endless and the same for everyone on the same day — the board is seeded by the date and alternates Medium and Hard. Perfect for comparing times with friends.

Winning & Sharing

When the board is fully correct the "Solved!" overlay appears (or "Daily solved!" for a daily board). Finishing all 11 campaign levels shows "Campaign complete! Endless daily puzzles unlocked."

• Next level → — continues the campaign or starts the next daily puzzle.
• 📋 Copy — copies a one-line bragging summary.
• 𝕏 Share / 👽 Reddit — open a "Your board" share card with your finished grid: 📋 Copy Image, ⬇️ Save as PNG, or post directly to 𝕏 / Reddit.