Get the full engine definition (topology, render config, pieces, setup FEN) for a game variant. Returns the resolved frontmatter used to render and play the game.

Game family (chess, draughts, go, reversi, shogi, xiangqi, mancala, morris, hex, landlords-game, backgammon, standard-52, bavarian-32, flower-48, double-six-dominoes, mahjong, standard-dice, agon, asalto, chaupar, dou-shou-qi, fanorona, halma, nyout, pachisi, royal-ur, senet, stern-halma, surakarta, tafl)

Variant slug (default: the family's default game)