Megiddo is an out-of-print variant of Pente played on a round board consisting of six rings connected by six spokes.
Each player in turn places a stone on one of the intersections in an attempt to get six pieces in a row in one of several configurations. A row of six could be either along a spoke, around a ring, or most interestingly, in a spiral from innermost to outermost rings. A win could also be achieved by capturing enough pairs of opposing pieces by bracketing them on either side
I can meet you in London the next time I'm there.