A daily brain-teaser, a collection of logic puzzles machine-checked to have exactly one solution, and hidden-role party games for four to ten friends — no board required.

Every logic grid, zebra, and knights-&-knaves puzzle here is run through a constraint solver before publication, which checks every possible arrangement and confirms exactly one of them satisfies all the clues — the puzzle only goes live once that's proven, not asserted. Riddles and math puzzles aren't the kind a solver can prove unique, so they carry no such badge.