Crossoku. Sudoku X.

Sudoku X — the diagonal twist that changes everything.

Crossoku is Diagonal Sudoku (also known as Sudoku X): a 9×9 grid where both main diagonals must also contain the digits 1–9 exactly once. This extra constraint creates 11 constraint regions instead of the standard 9, opening powerful solving strategies and making every puzzle feel fresh.

THE DIAGONAL DIFFERENCE
• Both main diagonals are full constraint regions, just like rows, columns, and boxes
• Diagonal interactions unlock techniques unavailable in standard Sudoku
• Puzzles are carefully generated so the diagonal constraint is always meaningful
• Same grid, a whole new layer of logic

SIX DIFFICULTY LEVELS
• Easy: Gentle introduction to diagonal logic — perfect for new players
• Medium: Diagonals start shaping every move
• Hard: Diagonal intersections become critical solving pivots
• Expert: Multi-region interactions demand precise thinking
• Pro: Advanced techniques and diagonal chains test your limits
• Master: The pinnacle — only the most rigorous logic survives

CAMPAIGN MODE
• 50 handcrafted puzzles across 5 progressive worlds
• Each world introduces a new technique to master
• Complete a world to unlock the next challenge
• Earn stars and track your solving mastery

DAILY CHALLENGES
• A fresh diagonal puzzle every day, the same for players worldwide
• Build your streak and track your calendar history
• Compete on global leaderboards and see how you rank
• Notifications tell you when a new puzzle is waiting

TECHNIQUE LIBRARY
• Browse and practice diagonal Sudoku techniques interactively
• Understand why each move works, not just where to place
• Progress from simple Singles to advanced diagonal eliminations
• Smart hints explain the technique behind every hint

ELEGANT DESIGN
• Clean, focused aesthetic — no clutter, no distractions
• Ten color themes with light and dark variants
• Refined typography readable at any size
• Smooth animations and native responsive feel
• Full portrait and landscape orientation support

SMART SOLVING TOOLS
• Pencil marks for annotating candidates in any cell
• Unlimited undo and redo — explore freely
• Optional error highlighting to catch mistakes early
• Auto-save so you never lose your progress
• Highlight matching numbers to identify patterns instantly

TRACK YOUR PROGRESS
• XP system with 100 levels to achieve
• 60 achievements in 6 categories to unlock
• Personal statistics per difficulty level
• Win streaks and personal best times
• Google Play Games integration for competing with friends
• Cloud sync keeps your progress safe across all devices

PLAY YOUR WAY
• Fully offline — play anywhere, anytime
• No account needed to start immediately
• 45+ languages with full localization
• TalkBack screen reader support for accessibility
• High contrast themes for comfortable viewing
• No forced tutorials — dive straight into puzzles
• Free with no paywalls

If you enjoy Sudoku and want a fresh strategic challenge without learning a completely different game, Crossoku is for you.

Download Crossoku and think diagonally.

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