Grid puzzles
Available nowThe original game. Rows of categories, columns of positions and visual clues you have to turn into eliminations. Three worlds, 200 levels each and three board sizes per level.
Deduction puzzles where you never have to guess
A rural postman with an extraordinary head for order. Every puzzle has exactly one solution, and you can always reach it by reasoning.
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Get it on Android in a few days
The CluePost universe
One postman, many ways to deduce
Everything in CluePost revolves around the post office and the clues. Each game is a different chapter of the same story, with the same underlying rule: the solution already exists, and you uncover it.
Bee World
In developmentOnce the postman finishes the ten worlds, he crosses into a dimension where he is a bee and the board is a honeycomb. The same logic on hexagons: six neighbours instead of four, and adjacency clues stop behaving the way you knew them.
The Dead Letter Office
On the drawing boardA different kind of thinking: pushing crates of undeliverable mail around the back room until each one sits where it belongs, without boxing yourself in. Less deduction, more planning every move before you make it.
The story
Three worlds released, ten planned
Each world has its own icon categories, its own character and its own chapter of the script, which unlocks as you progress.
The Farm
Don Ramiro has let every last animal escape and all he has left is a handful of scattered notes. You have to start somewhere.
The Cosmos
An abduction he did not see coming, and an alien fleet thrown into disarray by a meteor storm.
Ancient Egypt
The records of the kingdom, an impatient pharaoh and a vizier about to lose his head.
If you are new here
What a logic grid puzzle is
You may know them as Einstein riddles, zebra puzzles or logic problems. The idea is always the same: there are several categories — people, houses, animals, colours — and each element occupies exactly one position that you do not know. What you do have is a handful of clues relating some elements to others, and that is enough to reconstruct the entire solution.
The lovely part is that the answer already exists before you begin. You do not build it, you uncover it. Each clue trims the space of possibilities, and once you have applied them all, exactly one combination is left standing.
How it differs from sudoku
Sudoku hands you a half-filled grid and a fixed set of rules: each number once per row, per column and per region. All the information is on the board itself.
Here the board starts empty and the information arrives from outside, as clues. That changes the nature of the reasoning: in sudoku you hunt for gaps where only one number fits; in a deduction puzzle you translate statements about relationships — "the mill and the cow share a column", "the pig is not next to the hen" — into concrete eliminations on the grid. It feels closer to working a case than to filling in a table.
Why you never have to guess
A well-built deduction puzzle meets two conditions: it has exactly one solution, and that solution is reachable by applying the clues in some order, with no assumptions.
The first is easy to verify. The second is not: there are puzzles with a unique solution that you can only reach by trying a hypothesis and seeing whether it breaks. To the player that is indistinguishable from luck, and it is the difference between a puzzle that hooks you and one that frustrates you.
How that is guaranteed here: every
puzzle is generated and then solved by a solver that only applies
direct deductions. If the solver cannot finish it without guessing, that
puzzle is discarded and another one is generated. It is the only honest
way to promise that there is always a piece of reasoning left to do.
Handmade, and free
CluePost is developed by JSB Softworks, a one-person studio. The puzzle generator, the solver that validates them and the interface are all written from scratch; the hundred-plus icons and the story panels were created for this game.
The whole thing is playable without paying anything. There are no in-game purchases, no lives that run out and no waiting to continue. The Android version shows optional ads: watching them earns rewards, and not watching them blocks nothing.