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.

Cases open one after another across four places — Rookie Desk, City Beat, Night Shift and the Cold Case Vault — and each case card tells you what is new before you start, from your first lineup to bigger files with more suspects. Clues are not all handed over at once: every correct placement opens the next one, so the file grows as you work it. A wrong pick costs one of three hearts, and if you sit still for a while the clue that can move you forward gives a gentle pulse. Tap a cell to open the picker and choose a value, use the Hint button when a case genuinely stalls. After the last desk the case numbers keep going: reopened cold cases come back with new names and mirrored lineups, drawn more and more from the bigger files. It runs in the browser on phone and desktop, no download, no timer. Sudoku players tend to take to it immediately.