Originally posted by SwissGambitLoses - you just have to capture the complete opponent's army. In the GP example White would win as Black can make no move. It is not lucrative to play for a checkmate, as it would cost you a Queen for a worthless King most of the time...
Is that "loses" or "wins"?
There is also a variant called 'suicide chess' in which the goal is to lose all your pieces first, and the K is not royal.
1. e3 d6 2. Qg4 Bxg4 3. Kd1 Bxd1 4. a3 Bxc2 5. Ra2 Bxb1 6. Be2 Bxa2 7. b3
Bxb3 8. a4 Bxa4 9. Bd1 Bxd1 10. Ne2 Bxe2 11. g4 Bxg4 12. f3 Bxf3 13. h4
Bxh1 14. e4 Bxe4 15. d3 Bxd3 16. Bh6 gxh6 17. h5