Ringtrace

Tap an edge to cycle blank → line → × → blank. A clue says exactly how many of its four edges belong to the loop. The finished line must be one connected loop with no branches.

Watch a tiny real-engine example build a valid loop.

• Keyboard: focus the board, use Arrow keys, then Space/Enter to cycle. L marks line, X marks excluded, Delete clears.
• Nudge: highlights a forced public-rule deduction but never applies it.