Logic Grid Detective
Brain TrainingFree to playSolve who/where/when clue sets on a grid.
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How to Play
Logic Grid Detective is the classic deduction puzzle: a grid of suspects against attributes, and a few clues that rule pairings in or out. Each cell cycles through blank, check and cross, and the answer is the arrangement that satisfies every clue. Three cases, growing in size and in the number of clues.
Controls
- Mark — Tap a cell to cycle it: blank, check, cross
- Pause — P
Tips & Tricks
- 1A check clears any other check in the same row or column automatically, so the board cannot show two matches where one is allowed. That means a check is a commitment rather than a note, and a cross is the safer mark while you are still working.
- 2The grid is 3x3 for the first two cases and 4x4 for the third, with one, two and three clues. The 4x4 with three clues is the only one where you cannot start from a single statement — it needs two clues combined before anything is certain.
- 3Clues are of the form 'A is B' and 'A is not B', so a positive clue is worth crossing out an entire row except one cell, while a negative clue only kills one. Positive clues are worth finding first for exactly that reason.
- 4The clock runs 120, 105 and 90 seconds across three cases with no reset, and a wrong mark costs nothing — only the clock. Marking speculatively is therefore free, and the grid remembers it for you.
Frequently Asked Questions
What do the three tap states mean?
Blank, check and cross. A check marks a pairing as the answer and silently clears contradicting checks in the same row or column; a cross marks it as impossible. Cycling past a state and back is free.
How many cases are there?
Three: 3x3 with one clue on 120 seconds, 3x3 with two on 105, and 4x4 with three on 90. Each is generated rather than drawn from a fixed set, so the names and attributes change per run.
Can I play on my phone?
Yes. Cells are tapped directly on the canvas and cycling a cell through its states is a single tap, which suits a touch screen better than a drag would.
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