p.boxed.
  Moves are potentially played in two times: move a piece,
  and / or push or pull something with that unit.

p.
  Pieces have the same movement as in orthodox chess, but they cannot
  take other pieces in the usual way. Instead of the normal captures, pieces
  can pull or push other pieces, potentially off the board.
  The goal is to send the enemy king off the board.

p Each turn, a player has the following options:
ul
  li.
    Move one of his pieces normally, then optionally pull something as an
    effect of this move.
  li.
    Push any piece with one of his pieces, then optionally follow the pushed
    piece.

p
  | It seems easier to understand with some examples. For a detailed
  | introduction please visit 
  a(href="https://echekk.fr/spip.php?page=article&id_article=599") this page
  |  (in French).

figure.diagram-container
  .diagram
    | fen:rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR e1,e3,e4,c3,f3,g4,h5,d3,c4,b5,a6:
  figcaption Possible "pawn moves" in the initial position.

p.
  The e2 pawn can move to e3 and e4 as usual. It can also slide diagonally,
  being pushed by the bishop or the queen (which may or may not move along
  this line afterward). It can also go to c3, being pushed by the knight from
  g1; then the knight can move to e2, or stay motionless.
  Finally, the pawn can "take the king": this is a special move indicating that
  you want it to exit the board. Indeed it could be pushed off the board by the
  bishop or the queen.

p.
  Note: if an action is possible but you don't want to play a second part in
  a move, click on any empty square: this will send an empty move.

figure.diagram-container
  .diagram.diag12
    | fen:rnbqkbnr/ppp1pppp/8/3p4/8/2N5/PPPPPPPP/R1BQKBNR:
  .diagram.diag22
    | fen:rnbqkbnr/ppp1pppp/8/8/8/2p5/PPPPPPPP/RNBQKBNR:
  figcaption Pulling the d5 pawn to c3 (left: before, right: after).

ul
  li Pawns cannot pull (because they only move forward).
  li.
    When they could reach the square beyond the edge,
    pieces can exit the board by themselves, possibly dragging another piece
    out (friendly or enemy).

figure.diagram-container
  .diagram
    | fen:rnb1qbnr/pppkpppp/3p4/8/Q1P5/5NP1/PP1PPP1P/RNB1KB1R:
  figcaption.
    Check: the queen threatens to pull the king off the board along the a4-e8
    diagonal.

p.
  It is forbidden to undo a "move + action". For example here, white could
  push back the black bishop on g7 but not return to d4 then.

figure.diagram-container
  .diagram.diag12
    | fen:rnbqk1nr/ppppppbp/6p1/8/3B4/1P6/P1PPPPPP/RN1QKBNR:
  .diagram.diag22
    | fen:rnbqk1nr/pppppp1p/6p1/8/3b4/1P6/PBPPPPPP/RN1QKBNR:
  figcaption Pushing the d4 bishop to b2 (left: before, right: after).

p.
  Castling is possible as long as the king and rook have not moved and
  haven't been pushed or pulled (this differs from the chessvariants
  description).

h3 End of the game

p.
  The game ends when a push or pull action threatens to send the king off the
  board, and he has no way to escape it.

figure.diagram-container
  .diagram
    | fen:8/4B3/8/8/6Qk/8/4N3/K7:
  figcaption Dynamo checkmate ("Dynamate" :) )

p.
  The king cannot "take" on g4: this would just push the queen one step to the
  left, and she would then push the king beyond the 'h' file.
  There are no en-passant captures.

h3 Source

p
  a(href="https://www.chessvariants.com/mvopponent.dir/dynamo.html")
    | Dynamo chess
  |  on chessvariants.com. The short description given on 
  a(href="http://www.pion.ch/echecs/variante.php?jeu=dynamo") this page
  |  might help too.

p Inventors: Hans Kluever and Peter Kahl (1968)