Introduction

Chess has players playing as either White or Black pieces on one side of the chess board.

Regular Chess has players taking turns moving pieces of their own color, but in Decision Chess, both players move simultaneously. After selecting their moves, both pieces-in-play are played at the same time, they are called active pieces before being played.

The game starts symmetrically. That is, the side you start as doesn't matter, what matters is how both players play together.

Pieces can only be captured by those of the opposite color.

Left-clicking a piece shows its available moves (solid circles) and captures (outlined circles). Pieces can be selected, then moved, by clicking the destination or dragged to them.

Right-clicking a square highlights it. When you right click, then hold and drag to another square, releasing it creates arrows. They are usually used for planning moves. There is also the option to share arrows with your opponent to communicate with them. Arrows can be removed by left-clicking or redrawing them.

Once a move is chosen it is active. A transparent version of the piece is displayed at its destination until the opponent plays a move.

Coordinates

The board has dimensions of 8 by 8 squares, each labelled with a unique coordinate.

The columns are called files and are labelled left to right from "a" to "h", the rows are called ranks and are labelled bottom to top from "1" to "8". These labels start from white's orientation.

Squares are then labelled with coordinates starting with the file then the rank. For example, the white king starts on e1.

Try moving the pawn on d2 to d4.

Notice that the current and previous positions are highlighted on a move and are colored differently for both sides.

Pieces

There are 6 unique pieces. Each piece, other than the King, has a capture value representing it's strength and the advantage given to the opponent once captured.

• Pawns start by filling the second and seventh ranks with a value of 1.
• Rooks start on the corners of the board with a value of 5.
• Knights start next to rooks with a value of 3.
• Bishops start next to knights with a value of 3.
• Queens start on the d file and are next to the bishops of the c file. They have a value of 9.
• Kings are next to their queens and bishops on the e file.

Kings have no inherent value as the goal of the game is to force the king into a checkmate and it is illegal to capture them. They are the most important piece.

Checkmate is explained under the King's move lesson.

As the game progresses, the net piece capture value is displayed for the winning side to show a total advantage score. This is only displayed in live games, not in lessons and is displayed with the pieces summing to the score.

Superposition

In certain situations, your pieces may be able to move to squares occupied by pieces of the same color, but this is only allowed if the opponent also targets the same piece.

In such cases, the opponent captures your original piece but your active moving piece immediately counters with a recapture, takes the opponents piece, and lands on the destination square. This is called a super-position.

If your opponent selects a different active move instead, the recapture is illegal, the move is undone, an error sound is played, and you then must play a legal move.

In this position black will attempt to capture the pawn on d4 with their pawn on e5. Execute a recapture with the queen by moving it from d1 to d4.

Note well that recaptures are not counted as possible moves for a stalemate condition. A position with only recaptures possible would be considered a stalemate. Stalemate is explained under the King's moves lesson.

During games you have the option to execute some actions that affect the board or game. The command center holds these buttons and the running list of moves of the game.

Undo Move

In a live game, the player may be able to undo the last set of played moves. If the game is multiplayer, clicking the Undo Move button sends an undo offer to the opponent. If they accept, then the last move of both sides are undone. For AI or solo games, it automatically reverts the moves.

Resign

The resign option is available to forfeit a game as soon as the first set of moves have been played at any time.

Draw

In multiplayer games, a player has the option to offer a draw. The opponent will receive a draw request and if it is accepted, the game ends in a draw.

Cycle Themes

By clicking the cycle themes button the board will cycle between predefined color themes. This can also be performed by clicking the board and pressing "t". The default theme or set of cycled themes can be set in a logged in user's settings.

Flip

Flip the board orientation at any time with the flip button.

Move list

A list of moves is displayed and updated as the game is played. The first column is always white's move, the second is black's move, the row number is the turn the moves were played.

Moves can be revisited to review them by clicking the step buttons or clicking the row in the list. To resume playing you must step back to the latest move.

Once games are completed you may always revisit them for review or to share by going to the same url. If you have created an account, these games will show up under your profile.

These are the basics but clearly they don't cover everything.

If you are new to Chess complete the individual moves tutorials to learn how every piece moves and the king's moves lesson to learn about what the requirements are for a game over.

If you are familiar with Chess already and wish to learn the specific details of Decision Chess complete those tutorials next.