Logic Detective: Grid Puzzles

Four suspects, four jobs, four drinks — and a handful of clues. A logic grid puzzle (you may know it as Einstein's riddle, or the zebra puzzle) asks you to cross those categories in a grid: each clue lets you confirm one cell or rule out others, and deduction by deduction, the whole grid fills itself in. No vocabulary, no math, no guessing: by the end, every person is matched with their job and their drink, and everything fits.

Here, the case is worked by hand: tick, cross out — and tap a clue you've used up to strike it through.

EVERY CASE IS VERIFIED, CLUE BY CLUE

All 120 cases are generated, then checked one by one by a solver. Each has exactly one solution — double-checked by a second, independent algorithm, puzzle by puzzle — and a minimal set of clues: remove any single clue, and the case can no longer be solved. In other words: no filler clues, no ambiguity, ever. When you're stuck, the grid isn't being unfair — there is a next deduction, and it always exists.

Plenty of apps promise thousands of puzzles. These are 120 cases verified one by one — quality you can check, not volume.

DIFFICULTY THAT IS MEASURED, NOT GUESSED

Four tiers of 30 cases each. Their difficulty isn't set by gut feeling: it is measured on the puzzles themselves, by the length of the deduction chains the solver has to work through.
• EASY — 3 categories × 4 values, mostly direct clues: 3.1 deduction steps on average.
• MEDIUM — 3 × 5, a good third of indirect clues: 4.1 steps.
• TRICKY — 4 categories × 5 values, either/or clues: 6.6 steps.
• DIABOLICAL — 4 × 6, no direct clues at all, everything interlocks: 10.3 steps.
From one end of the game to the other, the share of indirect clues climbs from 15% to 100%.

A HELPING HAND THAT SHOWS ITS REASONING

• "Check the grid" compares your marks against the clues, without revealing anything.
• "Reveal a deduction" shows the next cell you can deduce — and quotes the clue that justifies it. The hint never hands you the answer: it shows you the reasoning.
• Made a mistake? One button erases only the faulty cells — never your correct work.

BUILT FOR QUIET DEDUCTION

• No timer on screen while you play: your time appears only once the case is solved.
• Live contradiction checking quietly circles cells that conflict — and switches off in the settings if you'd rather hunt alone.
• Close the app mid-case and you'll resume exactly where you left off.
• Light theme, dark theme, or follow the system; adjustable text size.
• Fully written in English, from the case titles to the last clue (and playable in French, German and Spanish).

SIMPLE AND HONEST

• Works entirely offline — no account, no sign-up.
• No ads, no videos to sit through, no lives, no energy.
• Your progress stays on your phone, and nowhere else.
• The first 30 cases are included. One single purchase — just one, no subscription — unlocks all 120, forever.

If you enjoy sudoku, crosswords, or the logic problems in puzzle magazines, you'll feel right at home: the same pleasure of pure deduction, in a grid that fills in cell by cell.

Open the first case. The clues are there, and so is the solution — all that's left is to deduce it.