p.boxed
  | Your pieces remain in an undefined state until they are moved.

p.
  Queens, rooks, bishops and knights begin the game in a reserve below
  the board, because their location isn't determined yet.
  At each turn, you can either move something already defined on the board, or
ol
  li move a piece from your reserve to any question mark, and then
  li move the now defined piece on the board.

p An undefined piece gives check if some specialization giving check exists.

figure.diagram-container
  .diagram
    | fen:uuuuu1uk/p2p1qp1/1p6/7p/7P/5N2/PP1P1PP1/UUUKU1UU:
  figcaption The white king cannot move, a rook might be on c8 or e8

h4 Details, special cases

p.
  At the first turn, you must select a square for the king anywhere on
  first rank. This deviates from the original intention of the author,
  but allows to "castle on move 1" without requiring a rook in a corner.

p.
  If one of your undefined pieces is captured, you first have to choose which
  one was captured from the reserve: place it at the capture location.

p.
  If after your move all your pieces are defined (and weren't before), then
  all pieces on board revert to undefined state, unless:
ul
  li.
    all your pieces (board + reserve) are now of the same type,
    in which case none is put back in reserve, or
  li.
    all opponent's pieces are of the same type, in which case
    they also remain defined.

figure.diagram-container
  .diagram.diag12
    | fen:uuu1kuuu/2p5/2n5/1p1ppppp/p4PPP/3N3Q/PPPPP1BB/1RRUK3:
  .diagram.diag22
    | fen:uuu1kuuu/2p5/2u5/1p1ppppp/p4PPP/3UU2U/PPPPP1UU/1UU1K3:
  figcaption.
    Before and after knight definition on d1 (moving to e3)

h3 More information

p
  | See the 
  a(href="https://www.bario-chess-checkers-chessphotography-spaceart.de/")
    | author's page
  |  with many examples and explanations, and the discussion 
  a(href="https://www.chessvariants.com/index/listcomments.php?order=DESC&itemid=Bario")
    | on chessvariants.com
  | .

p Inventor: Panos Louridas (1998)