Two Not Touch

How to play

• One click per cell, and it steps round: empty to star to dot and back to empty. A dot means "this one cannot be a star" and is only for your own bookkeeping.
• Right-click steps the other way, so a dot is one click too.
• On a phone, tap. Same three steps.

The rule the chip checks

• Exactly two stars in every row.
• Exactly two stars in every column.
• Exactly two stars in every outlined region.
• No two stars touch, not even diagonally.

The line under the board is what the real chip prints on O[7:0] for the grid you have placed. It has five things it can say and this page reproduces all five, including TWO NOT TOUCH, which only appears when every count is right and the only rule broken is the no-touch one. There is exactly one grid it answers (* TWO STARS *) to, and that was proved unique at the gate level.