Dark Prince: I agree that a capture of a piece is an easy and objective criterium and a clear indication that the game is still in progress. I like your idea to have a 'starting point', only it would be nice to have 1 rule for all variants, to keep it clear.

Maybe 50 moves without capture starting after move 50 for the 3 volcano variants (the small volcano variant is often slower than Fast Espionage) and 50 moves after move 25 for Open and Small fast, to keep it simple?