- Make a single loop with lines passing through the centers of cells, horizontally or vertically. The loop never crosses itself, branches off, or goes through the same cell twice.
- Lines must pass through all cells with black and white circles.
- Lines passing through white circles must pass straight through its cell, and make a right-angled turn in at least one of the cells next to the white circle.
- Lines passing through black circles must make a right-angled turn in its cell, then it must go straight through the next cell (till the middle of the second cell) on both sides.
1 unit comes with 30 puzzles with 60 pieces of paper.