Suction Chess

In this chess variant, pieces swap places instead of being removed from the board. In order for this to make sense, some of the other rules have also been changed, and in particular, the winning condition is different.

The result is a game very different from chess, but surprisingly interesting to play. In some ways the strategy resembles Go, in that there can be multiple battles occurring simultaneously in different parts of the board, and the players must choose which is the most important in any given move. Although pieces can't be removed from the board they can easily end up in positions where they don't contribute much to the game, and management of this is crucial.

The game was invented in Brighton, UK, circa 2010 and was played regularly by about 3 or 4 people around that time.

Setup

Setup is identical to standard chess.

Pieces

Pieces move identically to standard chess pieces, with the exception of pawns and kings, as described below.

Rules

The rules, setup and pieces are identical to standard chess, with the following rather major exceptions:

Pieces are never removed from the board. When a piece is taken it is not removed from the board but instead is moved to the square that was occupied by the taking piece at the start of the move. (In almost all cases this results in the two pieces swapping places, with the one exception being en passant.)

The king cannot move at all, except by being taken by one of the opponent's pieces. There is no castling.

Taking a king has no effect besides moving it. Consequently, there are no rules about check, checkmate or stalemate.

The goal is to "suck" the opponent's king to your own first rank. When the opponent's king arrives on the first rank, the game is won immediately.

Pawns don't promote, but instead just stay on the back rank where they can't move. (A pawn can still re-enter play after this happens, by being taken by an opponent piece.)

Pawns can move two squares forward whenever they are on the second rank, even if it's not their first move. (This is to avoid having to keep track of which pawns have moved previously.)

Notes

There are various strategies that occur naturally in this game:

Chains: a succession of your own pieces arranged such that each one is defended by the next, with the last one being on your back rank. The opponent's king can be passed down the chain and eventually sucked to the back rank, unless the opponent can distrupt the process. Setting up multiple chains is the key to winning the game.

Exchanges: rather than exchanging pieces, exchanges tend to take the form of both kings being moved the same distance toward their opposite rank.

Sidelining: pieces can't be removed from the board, but they can be put into positions where they become useless. In particular, it is very difficult for knights to escape from the corners. Setting up moves to take the opponent's pieces out of the action, and avoiding this happening to one's own pieces, is an important part of the strategy.

Same coloured bishops: you can move your opponent's black bishop onto a white square (or vice versa), but they can't move it back onto its original colour. One strategy is to make sure your opponent's bishops are both on white squares while your king is on a black square (or vice versa), making it impossible for their bishops to attack your king unless they move it onto a white square first.

re-deployment: typically, play tends to split into two simultaneous battles, one centred on each king. Sometimes pieces will need to be re-deployed from one battle to the other.

sente: as with Go, the control over the game tends to shift back and forth between the two players. We say the player in control has 'sente', meaning that they can make moves that force the other player to respond. Moves that give you sente are valuable and are an important part of the strategy. This happens more in Go and Suction Chess than in standard chess, because of the tendency of Go and Suction Chess to separate into multiple simultaneous sub-battles.

The usual forks and pins can occur as well, though they tend not to play as important a role as they do in normal chess.

The opening theory is a little strange, and it may be that this game would work better with a different initial setup. (We never experimented with that.) Generally, normal chess openings don't work well at all. It's not such a bad idea to move your queen into the centre of the board early on, since even if it gets sucked into a corner it can still easily get back into the action.

While compiling this page I discovered that there is another chess variant that is called "Suction Chess", invented by Ralph Betza in 1979. I can't find a lot of information about this, but it does seem to be a completely different game.