Suppose we're playing a version of chess where you lose if you repeat an earlier position (position = arrangement of pieces + who's move it is). We're down to the wire, and we've just arrived at the position after the 30th capture, with only the two kings left on the board. With best play, who wins?
I think the question originated with the British go player Matthew Macfadyen 6-dan, but was solved by John Rickard. Avoiding loops is a thing in go however the puzzle here requires zero knowledge of that game.
As far as I know the solution has never been published. So here we chess.stackexchange: good luck!
EDIT: With just the two kings, stalemate cannot happen. Assume there is no 50-move Rule & no Dead Position Rule. This problem does not concern these rules. And in any case, in compositions these rules are applicable by default only to retro problems, which this is not.