angel problem
game-theoretic game on an endless chessboard: a devil hinders an angel’s movement, and the angel tries to escape; each turn the angel jumps ≤k squares, and the devil adds a block on an empty square
en-US/ˈeɪnd͡ʒəl ˈpɹɑbləm/
en-GB/ˈeɪnd͡ʒəl ˈpɹɒbləm/