World
Place pieces on a board so every first-order sentence is true.
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A new set of daily puzzles, one for every kind of logic. Everyone gets the same puzzle each day, so you can compare notes in the club.
Puzzle day 1 · · · StatsSentences, liars and clues. Pure deduction.
Place pieces on a board so every first-order sentence is true.
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Knights tell the truth, knaves lie. Work out who is who.
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Match people, things and places from a list of clues.
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Put things in the grid so every rule holds.
One queen in every row, column and colored region, and no two touching.
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Queens with two stars in every row, column and region.
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Pitch one tent next to every tree. The numbers count tents per row and column.
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Place bulbs so every cell is lit and no two bulbs see each other.
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Decide which cells are black and which are white.
Shade cells to match the number clues and reveal a picture.
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Shade the sea so every number is an island of that size.
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Cut the grid into rectangles, each holding one number equal to its area.
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Draw one path or network through the grid.
Draw one loop. Each number says how many of its four sides the loop uses.
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Draw one loop through every pearl. Turn on black, go straight through white.
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Connect the islands with bridges. Each number counts its bridges.
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Digits, sums and sightlines.
Six by six sudoku, with a four by four starter. The bridge to Variant Sudoku.
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Fill the runs with digits 1 to 9 that add up to the clues, with no repeats.
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Build a city of heights. Edge numbers count how many buildings you can see.
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Short lessons climb from true and false to the exact techniques these puzzles use.
Start with truth and reasoning, then learn the moves each puzzle uses.
Every puzzle keeps an archive: add ?n= and a puzzle number to any puzzle page.