Grid Detective

#logic#deduction#clues#brain#detective

How to play

Tap a grid cell to open the picker and choose a value. Use the Hint button when stuck; tap the level pill to pick any level.

About Grid Detective

Grid Detective is a logic-grid puzzle, the kind sometimes called a zebra puzzle after the most famous example. You get a set of clues and a grid of attributes, and the answer is entirely determined by the clues — there is nothing to guess and nothing left to chance.

A typical puzzle has several categories that must be matched up one-to-one, and clues that constrain them indirectly: something is not next to something else, one attribute belongs to whoever has another. No single clue solves anything on its own. The solution comes from combining them, and the moment where two unremarkable clues intersect to eliminate a possibility is what the puzzle is for.

The productive technique is negative reasoning. Beginners hunt for what must be true; experienced solvers spend most of their time marking what cannot be true, because eliminations accumulate until only one option is left standing in a row. If you find yourself stuck, you have almost always stopped eliminating too early.

Everything here is deducible. There is never a point where you have to pick one of two options and see what happens — if a puzzle appears to require that, there is a clue you have not fully used yet. That guarantee is what makes logic grids satisfying rather than frustrating.

Tap a cell to open the picker and choose a value, and use the Hint button when a puzzle genuinely stalls. Tap the level pill to jump to any level. It runs in the browser on phone and desktop, no download, no timer. Sudoku players tend to take to it immediately.

Frequently asked questions

Do I ever have to guess?

No. Every puzzle is solvable by pure logic from the clues given. If a puzzle seems to need a guess, there is a clue that has not been fully applied yet.

What is a logic grid puzzle?

It is a deduction puzzle where several sets of attributes must be matched one-to-one using indirect clues. The clues rarely state an answer directly — you reach the solution by combining them and eliminating what is impossible.

How do I get better at these?

Concentrate on eliminating possibilities rather than finding certainties. Marking what cannot be true accumulates until only one option remains in a row or column, and most players who get stuck have stopped eliminating too early.

Can I choose which level to play?

Yes. Tap the level pill to jump to any level, and use the Hint button if a particular puzzle stalls.