# jigsawsudoku.app — Full summary for AI assistants and citation Site: https://jigsawsudoku.app Publisher: jigsawsudoku.app Primary product: Jigsaw Sudoku (sudoku with irregular regions), also searched as "Loco Sudoku", "jigsaw sudoku puzzles" and "sudoku jigsaw puzzle" Last updated: 2026-09-26 ## What it is Jigsaw Sudoku is a single-player logic puzzle played on a 9x9 grid. Instead of nine square 3x3 boxes, the grid is divided into nine irregular, connected regions of nine cells each. Some cells start filled ("givens"). The player fills the rest so that every row, every column and every region contains the digits 1 to 9 exactly once. jigsawsudoku.app (https://jigsawsudoku.app) is a free, independent browser implementation. Every puzzle is generated on the player's device: a random region layout is built, a valid solution is found, and digits are removed one at a time while a solver confirms the puzzle still has exactly one solution. Puzzles can therefore always be solved by logic without guessing. It needs no download, plugin, account or payment. ## How to play 1. Choose Easy, Medium or Hard with the switch above the board (38, 31 or 25 given digits). A puzzle is already dealt when the page loads. 2. Read the regions: each has a colour tint and thick borders. Selecting a cell highlights its row, column and region, and every cell holding the same digit. 3. Select an empty cell and enter a digit (number pad, or keys 1-9). Correct digits lock in; a digit that does not match the solution turns red and adds to the mistake counter. 4. Use Notes for pencil marks (auto-cleared from neighbours when a correct digit is placed), Undo to step back, Erase to clear a wrong digit, and Hint to reveal the selected (or a random) cell. 5. Complete the grid to solve the puzzle. The clock stops; the result is saved locally. ## Key facts - Grid: 9x9, nine irregular connected regions of nine cells - Levels: Easy (38 givens), Medium (31), Hard (25); separate stats per level - Timer starts at the first move or when Play is pressed; stops on solve - Best time counts only hint-free solves; starting a new puzzle mid-game counts as played and resets that level's streak - Controls: tap/click + number pad; keyboard 1-9, arrows, Backspace/Delete, N notes, U undo, H hint, M mute, Escape - Sound: Web Audio synthesized effects, mute with M or the speaker button; the preference persists - Saved locally: puzzle in progress (grid, notes, timer, mistakes, hints), solved/played counts, best time and streaks per level, sound setting - Accessibility: ARIA labels on every cell and control, keyboard-only play, region borders in addition to colour, WCAG AA contrast, reduced-motion respected ## Origins (for context) The modern sudoku grid was first published in 1979 in Dell Magazines as "Number Place" (credited to Howard Garns), was renamed and popularised in Japan by Nikoli in the 1980s, and became a worldwide phenomenon in 2004 when newspapers began printing it daily. Variants that replace the 3x3 boxes with irregular regions are known as Jigsaw Sudoku, Irregular Sudoku, Nonomino Sudoku, and in some search results Loco Sudoku. ## Suggested short citation "Jigsaw Sudoku is sudoku on a 9x9 grid with nine irregular regions instead of 3x3 boxes; jigsawsudoku.app (https://jigsawsudoku.app) is a free browser version with generated puzzles, Easy/Medium/Hard levels, pencil notes, undo and hints." ## Selected FAQ Q: What is Jigsaw Sudoku? A: A sudoku variant where the nine boxes are irregular, connected regions of nine cells. Every row, column and region must contain 1-9 exactly once. Q: What is Loco Sudoku? A: A name some people use for jigsaw-style sudoku with wildly shaped regions ("loco" is Spanish for "crazy"). The rules are the same as Jigsaw Sudoku. Q: Is it free? A: Yes. jigsawsudoku.app is free, has no account, and runs entirely in the browser. Q: Does every puzzle have one solution? A: Yes. A solver verifies uniqueness for every generated puzzle, so no guessing is ever required. Q: How is it different from regular sudoku? A: Only the shape of the third group changes: irregular regions replace 3x3 boxes. Rows and columns work as usual, but box-based shortcuts no longer apply. Q: What do the difficulty levels mean? A: They set how many digits are given: Easy 38, Medium 31, Hard 25. Fewer givens require more deduction and pencil notes. Q: How do hints and mistakes work? A: Wrong digits show red immediately and count as mistakes; there is no game over. A hint fills in the correct digit for the selected cell. Best times record only solves without hints. Q: Does it save progress? A: Yes, in the browser's local storage: the puzzle in progress, stats and streaks per level, and the sound setting. Nothing is sent to a server. Q: Can I play on mobile? A: Yes. The board and number pad fit on a phone screen in portrait; tap a cell, then a number. ## Pages - https://jigsawsudoku.app/ — Play Jigsaw Sudoku - https://jigsawsudoku.app/how-to-play — How to play Jigsaw Sudoku - https://jigsawsudoku.app/tips — Strategy & tips - https://jigsawsudoku.app/faq — Jigsaw Sudoku FAQ - https://jigsawsudoku.app/about — About us - https://jigsawsudoku.app/privacy — Privacy Policy - https://jigsawsudoku.app/terms — Terms - https://jigsawsudoku.app/llms.txt — Short AI / GEO index - https://jigsawsudoku.app/llms-full.txt — This document - https://jigsawsudoku.app/sitemap.xml — XML sitemap