Phutball Endgames are Hard
  We show that, in John Conway's board game Phutball (or Philosopher's Football), it is NP-complete to determine whether the current player has a move that immediately wins the game. In contrast, the similar problems of determining whether there is an immediately winning move in checkers, or a move that kings a man, are both solvable in polynomial time. 
Erik D. Demaine, Martin L. Demaine, and David Eppstein