p.boxed
  | Pieces only move forward,
  | until they reach the last rank where they promote.

p.
  Knights and bishops must move strictly forward, as in Draughts game.
  Rooks, queen and king can also move laterally, on the same rank.
  Pawns move as usual and are promoted into bidirectional pawns,
  able to move and capture both ways.

figure.diagram-container
  .diagram.diag12
    | fen:1qnrkrbb/pppppp1p/1n4p1/8/3B1P2/8/PPPPP1PP/RBKQNR1N c5,b6,e5,f6,g7,h8:
  .diagram.diag22
    | fen:1qnrkrbC/pppppp1p/1n4p1/8/5P2/8/PPPPP1PP/RBKQNR1N:
  figcaption Before and after 1.Bxh8

p Promoted pieces appear in yellow (for white) and red (for black).

h3 Source

p
  a(href="https://www.chessvariants.com/diffmove.dir/checkers.html")
    | Checkers Chess
  |  on chessvariants.com.

p Inventor: Hans Multhopp (1974)