p.boxed
  | Capture the ball, pass it among your pieces and bring it to the
  | center of the last rank.

p.
  At the beginning, there is a ball in the center of the 9x9 board.
  It doesn't move. The first piece to capture it will then hold the ball.

ul
  li.
    Capturing an enemy unit holding the ball both make the piece
    disappear and grab the ball.
  li "Capturing" a friendly unit pass the ball to it.

figure.diagram-container
  .diagram.diag12
    | fen:rnbqkwnbr/ppppp1ppp/9/5p3/4a4/9/2N4N1/PPPPPPPPP/R1BQKW1BR:
  .diagram.diag22
    | fen:rnbqkwnbr/ppppp1ppp/9/9/4s4/9/2N4N1/PPPPPPPPP/R1BQKW1BR:
  figcaption Left: before ...fxe5 (taking ball). Right: after ...fxe5.

p.
  The piece sitting to the right of the king is a wildebeest (W).
  It moves by jumping in L like a knight, or a little bit further:
  three squares in one direction then one aside.

h3 End of the game

p.
  The goal is to bring a piece holding the ball in one of the three
  central squares of the opposite side (files d, e or f).

figure.diagram-container
  .diagram.diag12
    | fen:rqnkb1nb1/pp1pppp1r/2p5p/4wW1p1/4S4/1P5B1/9/P1PPP1PPP/RQNK2NBR:
  .diagram.diag22
    | fen:rqnkb1nb1/pp1pppp1r/2p5p/4wY1p1/4P4/1P5B1/9/P1PPP1PPP/RQNK2NBR:
  figcaption.
    Left: before e5Pf6 (passing the ball).
    Right: after the move. Then Wxe9# cannot be prevented.

p.
  White pass the ball from the pawn at e5 to the wildebeest at f6.
  Then, since the black bishop on e8 cannot move white will win by taking it: Wxe9#.

h3 Source

p.
  A friend and I talked some day (in 2019) about a variant where pieces
  would hit a ball to bring it to the opposite side.
  This version is inspired by these preliminary trials,
  because hitting the ball led to somewhat blocked situations.