You Can Look Now.

The older children have been playing blindfold chess.  It's exactly like regular chess, except they have to face away from the board, call out their moves by notation only, and keep track of the entire game in their head.  I make their moves on the board, notate, and occasionally have to tell them that this or that move is not possible.  It is a LOT harder than it looks.  Elf says the middle game is hardest because that's when there are the most pieces on the board to keep track of.  During the beginning of the game, the pieces are all near their starting positions.  Endgame has very few pieces, usually.  Emperor kicked butt in this game, but many of his pieces are idle under this system, which almost never happens in a regular game.  It's good mental exercise, have you ever done this?