How to Use This Page

• Drag a domino from the tray onto the board, or tap a tray domino then tap two adjacent cells, to place it.
• Tap an already-selected tray domino again to rotate it 90° before placing it; keep tapping to cycle through all four orientations, then deselect it.
• Tap a placed domino to rotate it in place; drag a placed domino to move it elsewhere on the board.
• Every outlined region shows a rule -- an exact total, "all equal," "all different," a greater/less-than threshold, or no rule at all -- that its own cells must satisfy once filled.
• Once every cell in a region is filled, its outline turns solid with a checkmark if the rule holds, or tints with an X if it doesn't.
• The board is solved once every cell is covered and every region's rule holds.
• If you're signed in, leaving and coming back later picks up right where you left off.

Full Rules

• Every domino must be used exactly once, covering two adjacent empty cells.
• A domino can straddle two different regions at once -- each of its two ends counts only toward its own region's rule.
• Scoring rewards a faster solve; giving up before finishing scores 0.