About Catdoku
Catdoku is a logic puzzle disguised as a very cute cat-placement game. You get a square grid divided into coloured territories, and you need to place exactly one cat in each territory under a small set of rules that are easy to state and surprisingly demanding to satisfy.
If you have ever played Star Battle, Queens or any of the "one per row, one per region" family of puzzles, you already know the shape of the challenge. Catdoku takes that familiar ruleset, wraps it in pastel colours and unimpressed-looking cats, and gives you boards that start almost trivially and finish by requiring real deductive work.
What makes it satisfying is that there is no guessing involved. Every board has exactly one solution, and it can always be reached by pure reasoning: eliminate cells that cannot hold a cat, spot the region that only has one legal home left, and chain those deductions until the grid is full. When a puzzle clicks, it feels less like luck and more like you out-thought a small, furry adversary.
How to Play Catdoku
The board is a grid split into distinct regions by colour. Your job is to place cats so that every region ends up with exactly one cat, and no two cats sit in the same row or the same column.
Because rows and columns can each hold only a single cat, a cat you place immediately rules out its entire row and its entire column. That is the main engine of deduction: every placement shrinks the board for everything else, and the puzzle is really about finding the order in which those eliminations become decisive.
The second engine is the region rule. A region that has only one remaining legal cell must contain a cat — you can place it with certainty. Conversely, if a region's candidates are all inside one row, then that row must contain the region's cat, and every other cell in that row can be cleared.
Later boards tighten the geometry: narrow L-shaped regions, regions that snake around corners, and pairs of regions whose candidates overlap in ways that force one arrangement and forbid the others. Working through those interactions is the whole game.
There is no timer pressure by default. The puzzle is designed to be solved carefully, and mistakes can be undone cell by cell rather than forcing a restart.
Controls
- Place a cat — click or tap an empty cell
- Remove a cat — click or tap the placed cat again
- Mark a cell as empty — secondary mark, useful for tracking deductions without committing
- Undo / reset — buttons on screen; reset clears the board without losing your progress on other puzzles
- Zoom or pan — not required; boards are sized to fit the screen
Touch and mouse both work identically, which makes Catdoku a comfortable phone puzzle for a commute.
Tips and Strategies
Start with the smallest region. A region with three or four cells is nearly solved for you — most of its cells are already illegal, and the remaining candidates tell you where the cats must go.
Use rows and columns as fences. Once any cat is placed, cross out its whole row and column mentally. Most beginners fail to apply this aggressively enough and end up staring at a board that is more constrained than they realise.
Look for regions confined to a single row or column. If every candidate in a region shares a row, that row's cat is decided and every other cell in the row is dead. These are the free moves, and there are usually several per board.
Never guess. Catdoku boards have a single solution reachable by logic. If you find yourself picking a cell because it "feels right", you have missed a deduction — back up and look for a region whose candidates have narrowed to one.
Work from constraints, not from empty space. New players scan for where a cat could go; experienced players scan for where a cat cannot go. The eliminations do the work.
Why Players Keep Coming Back
Catdoku hits the sweet spot between a puzzle that is genuinely logical and a game that is pleasant to spend time with. There is no energy meter, no ad wall between puzzles and no punishment for thinking slowly, which makes it a rare thing in browser gaming: a puzzle that respects your attention.
The cats help more than you would expect. Placing the final feline on a board and watching the grid fill up is a small but real reward, and the theme keeps the whole thing light even when a board has you stumped for minutes.
And because the rules are so clean, it scales: the same three conditions that make the first board easy make the twentieth board hard, without any added complexity or new mechanic to learn.
Frequently Asked Questions
Is Catdoku free? Yes, completely free to play on holearena.com with no download or account.
How many cats go on each board? One cat per region, and because regions cover the whole grid, the number of cats matches the number of regions. Rows and columns each hold exactly one.
Do I need to guess? No. Every puzzle has a single solution that can be reached by deduction alone. If you feel stuck, there is always a constraint you have not applied yet.
Is it the same as Sudoku? It is a cousin rather than a clone. Sudoku uses one-per-row/column/box with numbers; Catdoku uses one-per-row/column/region with irregular, coloured territories. The deduction mindset transfers, the specific techniques do not.
Can I play on my phone? Yes, the controls are tap-based and the board fits mobile screens comfortably.
