p.boxed
  | If a piece is attacked and cannot move out of attack, it is captured.

p.
  Any piece that is attacked, but which cannot escape capture by moving away,
  capturing the attacking piece, or interposing the attacking piece is
  considered to be mated, and is removed from the board.
  Note that such a move does not need to be played: if a piece is attacked
  but not mated, it is not removed.
  Thus, kings and other pieces may remain under check.

p.
  Pieces cannot be taken in the normal way, only by the "mate-capture"
  described above.

figure.diagram-container
  .diagram
    | fen:rnbqkbnr/p1pppppp/8/8/1P6/2N5/P1PPPPPP/RNBQKBNR:
  figcaption After 1.b4 b5 2.Nc3X the b5 pawn is "mate-captured"

p.
  Note about moves notation: since captures do not occur on final squares,
  an "X" mark is appended to the move to indicate a capture.
  To keep notation short the potential list of captured squares is not written.

h3 End of the game

p The game ends when a king is "mate-captured".

h3 Source

p
  a(href="https://www.chessvariants.com/difftaking.dir/allmate.html") Allmate chess
  |  on chessvariants.com.