Uses a specialized version of a drop, where a piece or pawn is placed on a usually vacant cell as an extended move type of one or more pieces already on the board, as designated by the rules for that specific game . The piece that is thus gated in usually would have been off-board in reserve (aka, a pocket piece), although gating of on-board pieces is possible.
To give some examples, a piece that is gated in might enter into play by being placed on:
(a) the starting cell of a piece or pawn that just moved;
(b) a cell just vacated by a pawn or piece (not necessarily the starting cell);
(c) a vacant cell which is under the influence of a pawn or piece (a projected gated piece);
(d) an occupied cell and replacing a piece currently on the board that has reached a given cell or one of a predefined set of cells (promotion);
or a piece already in play might
(e) be teleported to another cell on the board (example: castling).
Gating is normally considered an exclusive move type, but may be combined with another move type, if the rules permit (such as a capture or another form of gating). Typically only one of these methods would be expected to exist in a given game which deploys gating. What differentiates gating from being a drop, is that gating is governed by one or more pieces on the board. Without this relationship to a piece or pieces on the board, the move would be a regular drop, as is seen with enemy pieces that are captured in Bughouse or Shogi. In addition, gating is usually done during a play in a game, unlike a drop which can be done before any pieces are moved.
