looks like the way to win this is to surround a corner board (top for white, bottom for black) with pawns and have the king in the inner square to block any pieces leaving (the king can't leave its board). (pawns get promoted to a queen on reaching the furthest side rather than the other side of a board) This creates an impenetrable fortress that nobody can dismantle? e.g. for black in bottom left, x=any piece (except knight); p=pawn; k=king: pppppppp xxxxxxxp xxxxxxxp xxxxxxxp xxxxxxxp xxxxxxxp xxxxxxxp xxxxxxxK

Great idea! It also works on the side of the board, I couldn't help building it out: https://onemillionchessboards.com/#4363,6

you are eeeeevil

I like that

Neat, though I expected every individual board to have "turns" - I didn't expect that I could just pick a random board, liberate the black queen, and have her clean up every single white piece on the board without my "opponent" getting to do anything in return.