Dominosa
Pair every cell once. Use every domino type exactly once.
Pair every cell once and use every number pair exactly once.
Solved
More · campaign map, Daily archive, Practice setup & exact tools
Campaign 90
1–30 Easy 5×4 · 31–60 Standard 7×6 · 61–90 Challenge 8×7.
Daily archive
Selected day: 0/3 · streak 0 days.
Generated Practice
Practice is admitted only after the exact-cover solver confirms one solution.
Board tools
Recent solves
Guided progression
Need technique practice instead of another full puzzle? Open the preserved V0.222 Path 50 without moving the specialist Lab onto the first screen.
Duplicates surface immediately
If the same unordered pair is used twice, both placements are flagged before you finish the board.
X marks stay first-class
Exclude impossible edges without committing a domino. Right-click near an edge on desktop or use X-mark on touch.
Hints explain, then apply
Hint names the deduction first; Apply Hint is a separate action, so assistance never silently plays a move.
Exact replay is portable
Campaign, archived Daily and generated Practice boards can be recreated from a compact exact-puzzle link.