Kittydoku

Goal

Fill the grid with kittens (or digits) so that every row, every column and every region holds each cat exactly once. The cats already placed at the start are fixed. Every grid has a single solution and can be solved by reasoning: guessing is never necessary.

The grids

• 4 × 4: four cats, 2 × 2 regions.
• 6 × 6: six cats, 2 × 3 regions.
• 9 × 9: nine cats, 3 × 3 regions.

The size depends on the level, or can be picked in the options. The cats on the grid change every game; the Digits button replaces the cats with numbers, or shows both, for easier reading.

Solo play

• Tap a cat in the basket, then the cells where it goes: the chosen cat stays armed and purrs. You can also tap a cell first, then a cat.
• Notes (N key): pencil small cat heads in a cell to keep track of the possibilities.
• Erase, Undo (Ctrl + Z), Check (spots misplaced cats) and Hint are always at hand.
• The autopilot solves the grid before your eyes, step by step, explaining every deduction. The game then counts for neither records nor stars.
• The stars reward three feats: no hint, at most one mistake and a time under the reference time.

The grid duel

Two players on the same device, against the AI or online, work on one shared grid, taking turns.

• On your turn, pick a cat and an empty cell, then tap Place the cat (or tap the cell again, or press Enter).
• Right answer: it earns 10, and 10 more for every row, column or region that cat completes.
• Mistake: it costs 5; the cell stays empty, that cat is crossed out in that cell for everyone and the turn passes.
• The game ends when the grid is full. The higher total wins.

Levels

• Easy: 4 × 4.
• Medium: 6 × 6.
• Hard: 9 × 9, singles only.
• Expert: 9 × 9, with pointing, pairs or triples.
• Diabolical: 9 × 9, with X-Wing, XY-Wing or quads.

About the AI

Every grid is drawn from a random solution, then emptied cell by cell as long as an exhaustive solver confirms the solution remains unique. A second solver reasons like a human with fourteen techniques; a grid's level matches the most advanced technique it needs. The same solver provides the hints and the autopilot. Facing you, the AI plays what its logic shows it: at low levels it gets distracted and makes mistakes, at high levels it lets almost nothing slip, counts the bonuses and avoids handing a nearly complete line to its opponent.