Go phase: place and capture stones as in Go. Ends when both players pass in a row.
Hex phase: starts automatically after the double pass. No more captures — place stones until one side connects. Black connects left↔right, White connects top↔bottom. The faint diagonal lines show the extra adjacency that makes the square grid behave like a Hex board.
Full rules: en.wikipedia.org/wiki/User:JoDu987/xGo