How to play
Fill every square with a dot or a ring. Tap a square once for a dot, again for a ring, a third time to clear it. Dark squares are given.
- Balance: every row and column has as many dots as rings.
- No three: never three of the same in a row or column.
- All different: no two rows, and no two columns, are identical.
A worked example
Take this row. Two dots sit side by side, and there are rings further along.
Step 1. A third dot next to the two dots would make three in a row, so the third square must be a ring.
Step 2. The row now has two dots and three rings. It needs three of each, so the last empty square is a dot.
Every square was forced by a rule, so you never need to guess.
Every puzzle has exactly one answer and can be solved by logic alone. Rule breaks turn the squares red as you play. A hint adds 15 seconds. Use the arrow keys and Space if you prefer the keyboard.