Crux: Daily Logic Puzzles

Crux (n.): a puzzling or difficult problem; an unsolved question. Crux is a daily logic-grid puzzle app for people who enjoy thinking things through. Each puzzle is a classic deduction grid (the kind you may know as an Einstein or Zebra puzzle): read the clues, eliminate what cannot be true, and work out how everything fits. SEVERAL NEW PUZZLES EVERY DAY Each day brings fresh grids across multiple difficulties, from the quick Hunch up through Expert, with richer clue types as the challenge grows. Optional narrative themes turn categories into short story clues, so the same logical workout feels different from day to day. Build streaks, earn achievements, and track your progress over time. PLAY THE PAST Browse the Archive to replay puzzles from earlier days. Premium unlocks the full history since launch. BUILD YOUR OWN Crux is also a puzzle engine. • Create unique grids in the Custom Builder • Customize theme, difficulty, and size • Control auto-generated clues or craft them step by step • Save favorites to replay anytime LEARN THE LOGIC New to logic grids? The interactive tutorial walks you through cross-referencing and elimination until the method clicks. DESIGNED WITH CARE • Clean, focused interface with dark and light mode • Check answers as you go (Premium) • Optional streak reminders so you do not lose a run • Six languages: English, German, Spanish, French, Italian, Portuguese • Curated puzzle packs to work through at your own pace • Export puzzles to PDF to print and share • Works offline. Great for commutes and travel • No ads • Optional analytics. You choose whether to share usage data FAIR PRICING Crux is free to download with daily puzzles included. One optional, one-time Premium purchase unlocks everything below across your devices. No subscription. • Full Daily Archive • Unlimited Custom Builder • Mid-puzzle answer checking • Print and PDF export • Hard and Expert daily puzzles • More puzzle packs Sharpen your mind. Find the connections. Solve the Crux.