The Chess Variant Pages

In The Bin

Designed by Darren Izzard

Introduction and Background

This is a game that I put together in early July 1999 as a test game for a temporal difference game-playing program I wrote, and that is how most of the play-testing has been done. However, it turned out to be quite playable (in my opinion) so here are the rules if you want to try it out!

The game centers around a bin, from which players may select their pieces during the game. The bin also controls which pieces may be captured, and each capture and piece selection affects the legality of future captures and piece selections. Forward planning therefore becomes essential.

The Board

The game is played on a 9x9 board, the central square of which is the "bin". No piece may move onto the bin. The three squares above the bin are black's "hot spots" (denoted by a +), while the three squares below the bin are white's hot spots (marked with a *).

This is the initial layout of the board:-

Graphical Diagram
ASCII Diagram
Initial Layout


Note that the board initially only contains a white king and a black king. The players select their other pieces during the game from the bin.

At the beginning, the bin contains the following pieces in the quantities specified:-

All pieces in the bin at any point in the game are neutral. They belong to neither player until they are selected. Therefore, pieces need to be able to switch colour quite easily. For this reason, it may be a good idea to use tiles to represent the pieces, which can be flipped over to be either black or white as needed.

The Pieces

The pieces and their moves are mostly as in normal chess. The additional pieces, summarised below, can be found in the Chess Variants Pages' Piececlopedia.

Note that kings may not move onto any hot spot, but other pieces may do so. Castling does not exist in this game.

All captured pieces return to the bin, and may be re-selected by either player. Captures may only be made if allowed by the bin-state rule. If a capture takes place, the player gets an extra move thanks to the capture rule.

All moves are subject to the board-state rule. See also the selection move and the push move.

Here are the additional pieces:-

Ferz (general)The Ferz moves one square diagonally, and captures in the same way.
NightriderThe Nightrider is to the knight what the bishop is to the ferz, or what the rook is to the wazir. Basically, it moves a series of knight's moves in a straight line until it hits something upon landing after one of the knight's moves (or it reaches the edge of the board!).
Wazir (vizier)The Wazir moves one square orthogonally, and captures in the same way.

The Rules

The object of the game is to mate your opponent's king. One slight variation is to make the objective "get your opponent's king in the bin," but this basically involves making one extra move after a checkmate!

I've given most of the moves and rules peculiar to "In The Bin" names, and each one is given its own section here.

The Selection Move: When a player takes a piece out of the bin and adds it to their army, it is known as a "selection." The piece takes on the player's colour (black or white) and is placed on any of that player's hot spots. A selection counts as a single move. Selections may be disallowed according to the bin-state rule and the board-state rule. You cannot make a selection if it would leave your king in check, but you can make one if it would get you out of check.

The Push Move: If there is a piece on a player's hot spot, they may perform a "push move". This moves the pieces on the hot spots into the bin. This allows players to push both their own and their opponents' pieces into the bin. Pushes cannot be "selective" - that is, when a push move occurs, all pieces on all of a player's hot spots are pushed. If there are two pieces on a single player's hot spots, the player cannot push one and not the other. When a piece enters the bin, it loses its colour and becomes neutral again. (Allowing players to push their own pieces into the bin enables piece exchanges, where a player may exchange one piece for another.) According to the capture rule, any push move gives the player an extra move, which allows a pushed piece which previously belonged to the opponent to be added to a player's own army, before the opponent can move again. Pushes may be disallowed according to the bin-state rule and the board-state rule. You cannot make a push if it would leave your king in check, but you can make one if it would get you out of check.

The Board-State Rule: Rules like this one are often found in other games. No move may cause the board to contain exactly the same pieces in exactly the same positions as at any earlier point in the game. (If the positions are identical apart from a missing or extra piece, that counts as different.)

The Bin-State Rule: This can cause some confusion when learning the game, but it is the core of "In The Bin" so I'll try to explain it clearly. Basically, no capture, selection or push may cause the bin to contain completely and exactly the same set of pieces that it contained earlier in the game. By a "set of pieces," I mean the entire contents of the bin (subsets of the bin's contents are ignored). Also, the rule is not concerned with the exact pieces, or who owned them in the past - just the number of pieces of each type. To explain this, imagine the queens were called Emma and Anna. If the bin contained just Emma and three wazirs, then Emma was selected, Anna could not be captured until the bin's contents had changed because the bin had contained one queen and three wazirs in the past.

In an attempt to clarify this rule further, here's another example. If, at some point earlier in the game, the bin contained two rooks and three knights, and now it contains just two rooks and two knights, no capture or push of a knight is allowed. If someone captures a nightrider (provided the bin has never contained two rooks, two knights and a nightrider), knight captures and pushes become allowed again, as long as the bin has never contained two rooks, a nightrider and three knights.

And one more example. If, earlier in the game, the bin contained a queen and three bishops, and now it contains two queens and three bishops, a queen cannot be selected by either player until either another piece has been added to the bin (provided such a move obeys this rule) or one of the bishops has been selected (which must also obey this rule).

To make this easier to grasp if you're still having difficulty, whenever you do anything that alters the current contents of the bin, write down the number of each type of piece that are in the bin before you make that move. Then, whenever you are thinking of making a move that would alter the contents of the bin, note down the number of each type of piece that would be in the bin if you made that move, and compare it against the list of earlier bin-states that you've been writing down. If it completely and exactly matches any previous state, the move is disallowed. If it does not match any previous state, the move is allowed.

The Capture Rule: Whenever a piece is added to the bin, the player responsible for adding that piece to the bin gets an extra move. If they add another piece to the bin in that move, they get another extra one. This can continue as long as the player continues to add pieces to the bin, either by capturing or by pushing.

Notes and Strategy

The most powerful piece is the queen. The second most powerful seems to be the nightrider. Therefore, a good first move is to select a queen, and, assuming the other player has also selected a queen, your next selection should be a nightrider.

If you can manage it, you should try to control the bin by keeping your opponent in check as much as possible. This prevents them from selecting extra pieces.

A good memory of past bin positions is vital if you're going to win. Remember that, unlike in normal chess, some pieces cannot be captured if the bin-state rule says so. These pieces can be moved risk-free through an opponent's defence, right up to their king! Conversely, having a swarm of pieces attack your king, none of which you can capture, is extremely frustrating.

Although captures and pushes get you extra moves, don't get carried away setting up long strings of captures so you can get extra moves. It's more important to build up a defence than to get extra moves.

I had originally assumed that the first few moves of each game would be devoted to selecting pieces. This is not so. As soon as a player gets a piece that can make long moves, check becomes possible, and it's a good idea to pursue it as soon as possible. The first person to achieve check can gain a huge advantage as far as selections are concerned.

There's a lot more I could say on this game, but I'll leave the rest for you to discover for yourself, if you're interested.

Thanks to Ben Good for pointing out a problem with diagonally-moving pieces in an earlier version of the rules.

Page written by Darren Izzard.
Page created 15th July 1999. Last modified: September 7, 1999.