Crumble is a turn-based strategy game for 2 players. The first player controls the black pieces, the second controls the white. Each player tries to connect their own pieces together in chains of neighbors. A player wins if one of their chains touches all four sides of the game board at the same time.



Not neighbors

Not neighbors

There are many different piece sizes - in fact there is no limit! In rare cases you may need to cut fresh pieces out of construction paper, or in casual games both players may agree to restrict the pieces to only those you have available. The standard set that comes with the game is almost always enough though.

Although they can have any size, each piece must be either a perfect square, or a rectangle that's a perfect half-square.

Players may agree on any starting position. 6x6 crumble, shown above, is the standard for competitive play, and recommended for most games. In time, 8x8 crumble may become the standard.

Black wins! In this sample position, the pieces making up the winning chain of neighbors are indicated in red. See how at least one piece in that chain touches each of the four sides of the board.

Taking Your Turn

When it's your turn, you have the choice to do either a split or a join, as described below. You can't pass your turn, so you have to choose one or the other. After you've done the join or split, you can choose either to end your turn right there, or to swap the color of one of your pieces with the color of one of your opponent's pieces, as described below. Use your turn to try to make your own chains of neighboring pieces longer and less vulnerable to being broken up, and to shorten those of your opponent.



Two of your squares can become a rectangle. To do this, pick the affected pieces up off the board, and replace them with a single piece of the appropriate size and shape.

One of your rectangles can become two squares.

Two of your rectangles can become a square.

One of your squares can become two rectangles.

Any of your pieces with a square outline can become a square.

A single straight cut can split as many of your pieces as you want.

Any of your pieces with a half-square rectangle outline can become a rectangle.

The cut can run along existing edges, even of your opponent's pieces.


On your turn, after you've performed a split or join, you have the option to perform a swap. This involves changing one and only one of your freshly split or joined pieces to your opponent's color, and changing one and only one of your opponent's pieces to your color. We call this 'swapping into' your opponent's piece. To explain swapping, we first distinguish between two types of neighboring pieces:

When two corners of one piece touch two corners of another piece, we call those 'two-point' neighbors.

These pieces are neighbors, but not two-point neighbors.

As shown below, your piece may swap through any number of your opponent's pieces, so long as they are all two-point neighbors.

Black first splits the square, and then swaps one of the resulting black rectangles into the white piece that is a two-point neighbor with it.
Black first splits the square, and then is able to swap through all of those white pieces on a single turn, because they are all two-point neighbors, and they are not Black's own pieces. It should be understood that the black swapping piece swaps first into one neighbor, turning it black, then into the next, and the next, and so on; so that it is as if the black piece were actually traveling along the swapping path. In practice players may only physically change the first and last pieces in the swapping path, but the full set of swaps is understood to take place each individually. This progression of the swapping piece through the swap path is graphically illustrated in the next section.

Things That Can Happen While Swapping

Whenever you swap, each step you take along the swapping path is treated as a swap of its own, that changes the configuration of color on the board. If one of those steps wins the game for either player, then the turn ends and the game is over.

Each step can also result in either player's pieces being 'captured' if they are surrounded by opposing pieces that neighbor each other in a ring around the pieces to be captured. See the top of this document for an explanation of what a neighbor is. Captured pieces take on the color of the pieces that captured them. The following example illustrates every aspect of capturing.

Black will split the rectangle on the left, and then swap one of the resulting squares through each of the indicated white pieces, all in a single turn.

After the first swap, the white piece is surrounded by a ring of neighboring black pieces.

Because it is surrounded, the white piece is 'captured', and becomes black.

Black continues to swap on the same turn, and surrounds two white pieces.

Both white pieces are captured.

Black continues to swap on the same turn; this time Black's own pieces are surrounded by White.

They are also captured.

Black continues to swap on the same turn, and this time the swapping piece itself is surrounded.

It is captured. Black can't continue swapping without a piece to swap, so the turn ends.

It's worth noting that Black could have ended the turn before any one of those swaps. Black also could have swapped backwards, into pieces that had already been swapped through. This is useful, for example, if you want to swap into one area to do a bunch of captures, and then swap out of that area to get to your final destination.

It's also worth noting that pieces must be fully surrounded in order to be captured. If one or more pieces are surrounded against the edge of the board, as is the case with the lone black square on the left edge of the above diagrams, there is no capture.

Drawn Games

Both players may agree at any time to declare a game drawn. But there is also one situation where a game is automatically drawn: if all the pieces that each player has split or joined on their most recent turn were also involved in splits or joins on that player's previous two turns, and if both sides have swapped into the same piece on the most recent turn and the previous two turns, then the game is declared a draw.