Puzzle rules
How every puzzle in the library works, explained from scratch. Pick a category, or jump straight to a puzzle.
Games
Classic puzzle games with number placement and logic.
Logic
Deductive reasoning, pattern recognition, and codebreaking.
Math
Mathematical riddles, brain teasers, and number challenges.
Words
Word-based puzzles: scrambles, searches, and ciphers.
Grid
Grid-based puzzles with spatial reasoning and constraints.
- KakuroFill number sums into a crossword-style grid.
- SkyscrapersDeduce building heights from edge visibility clues.
- BinairoFill a grid with 0s and 1s following three simple rules.
- Star BattlePlace stars so each row, column, and region has the right count.
- Light Up (Akari)Place light bulbs to illuminate every cell without conflicts.
- SuguruFill numbered groups so no identical digits touch.
- SlitherlinkDraw a single loop on grid edges guided by number clues.
- HashiConnect islands with bridges to form a single network.
- Nurikabe
- Shikaku
- Aquarium
- Hitori
Sudoku Puzzles
Classic Sudoku and its variants: Killer, Samurai, Jigsaw, KenKen, and Futoshiki.
- SudokuFill a 9×9 grid so every row, column, and box contains 1–9.
- Killer SudokuSudoku with cage sums — no repeated digits in any cage.
- Samurai SudokuFive overlapping 9×9 Sudoku grids — solve them all at once.
- Jigsaw SudokuSudoku with irregular regions instead of standard 3×3 boxes.
- KenKenCombine arithmetic and Latin square logic in caged grids.
- FutoshikiPlace digits with inequality constraints between cells.
Want more than the rules? Walk through a puzzle step by step.