WARNING: What follows is a game only a Geek could love.

Today’s design is a twist on the venerable game of chess, via quantum mechanics (See…I warned you).

If you’re the kind of savvy reader that hangs out at the Chrome Cow, you doubtless are familiar with a certain theoretical feline belonging to one Erwin Schrödinger. This cat has the misfortune to be confined in a box with a deadly device that has a 50-50 chance of triggering with an hour. At the end of the hour, goes the thought experiment, the cat, sealed from observation inside the box, is neither dead or alive, but is in superposition, a combination of these possible states. The cat does not live or die until the box is opened by an observer, who through the act of observation collapses the possible dead/alive states of the cat into one or the other state.

So what’s that got to do with Chess? What, indeed!

Enter Superpositional Chess (Super Chess? EigenChess? Quantum Chess? Schrödinger’s Pawn?).

Like Schrödinger’s experiment with the Cat, mine too is wholly theoretical, so to follow along you will need the following imaginary supplies:

• Two Chess Boards
• Two Sets of Chess Pieces

Set up both boards in the traditional manner. The players will take turns as per usual, but each player will move one piece of their color on each board, each turn.

If each player moved the same piece on each board to the same spot, the game would be identical to standard chess. It’s when the two moves diverge that things get interesting.

In this example, the white Knight has two potential legal moves.

If, on the two separate chess boards, he moves to each of these legal spots:
 

 The superpositional board is the additive result of Boards A & B.  In the above example, the knight is said to be superpositional, it exists only potentially in both spots.

So before things get too confusing, here are the rules:

Basic Definitions

• Each board is set up like a traditional chess game
• Both boards have the same color pieces facing the same player
• If two of the same type of pieces of the same color occupy the same space on both boards, that piece Exists in that space.
• Only one piece can Exist in one space at any given time.
• At the beginning of the game, before anyone has moved,
• All pieces Exist
• If two of the same pieces of the same color occupy different spaces on both boards, those pieces are Superpositional.
• See example above
• Only two Superpositional pieces of any color and any type can occupy the same space:

• Existing pieces take precedence over Superpositional pieces
• No move can be made that creates a Superpositional piece on a space occupied by an Existing piece

Player’s Turn

• Movement Round
• Player may move a piece of his color on each board, OR
• Collapse a Superpositional piece
• Player chooses two Superpositional pieces of the same type and color
• Player moves one of those pieces  to match the position of the matching type of piece on the other board
• That piece now Exists (this example follows on from the Knight example above):

Resolution Phase

Two Superpositional pieces of different colors may occupy the same space, but what happens when one of those pieces is Collapsed, and now Exists in that space?

Above we see four Superpositional pieces.

Black chooses to Collapse their Pawn. At then end of Black’s turn, we have a Black Pawn that Exists in the same space as a Superpositional White Knight. This is not allowed, so White now has a Resolution Phase to correct the problem:

In the above example, White chooses to Collapse the Knight to the space not occupied by the Black Pawn. If White had chosen to Collapse the Knight to the same space as the Black Pawn, the White Knight would have been forfeit.

• The first piece to Exist in a given square captures any piece that comes to occupy that space in the resulting Resolution Phase.

It is very likely as the game progresses that one move will trigger a cascade of alternating Resolution Phases.

• White’s move requires a Black Resolution Phase
• Black’s Resolution Phase requires a White Resolution Phase
• And so on…

 

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Threat and Check

For Existing pieces, the endgame rules of Check and Checkmate are the same as regular chess. It is when we bring Superpositional pieces into the mix that we need new rules.

Threat

• When a Superpositional piece is placed such that it can execute a capture move on a King (Existing or Superpositional) the next turn, the player that moved it there must announce "Threat"
• Threat is one step less serious than Check
• The player would have to spend their next turn Collapsing the piece for it to escalate into a Check:

• When an Existing piece is placed such that it can execute a capture move on a Superpositional King the next turn, the player that moved it there must announce "Threat"
• Threat is one step less serious than Check
• The Threatened player can Collapse their King to safety:

What about the case where two Superpositional pieces are threatening two Superpositional kings?

This is still classified as a Threat.

• A Check or Checkmate is only possible when an Existing King is in peril from an Existing enemy piece.

Threat, Check and Checkmate must be announced both in in the Movement Phase and the Resolution Phase

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Optional Rules

Entanglement

• For all pieces except the king and queen
• Number the pieces
• Pawns 1-8
• Knights 1-2
• etc.
• When placing the pieces in their initial position
• Lowest number go on the left
• So the leftmost pawn is #1, the rightmost #8
• Leftmost Knight is #1, rightmost is #2
• You may only collapse pieces
• Of the same Color
• Type, AND
• Number

Final Thoughts

This game (I kind of like the name EigenChess) might be a great way to introduce young Chess players to the world of quantum mechanics, and build up some intuition for some of the non-intuitive aspects of that branch of scientific inquiry.

If someone really wanted to play this on an ongoing basis, the easiest approach is probably a software solution to manage the boards and states of the pieces.

However, you could also set up two physical boards, place a top-down video camera over each board and then superimpose the two video streams, which would give you a result like the Superpositional Board used in the above illustrations.

Either way, drop me a line and let me know how it works…};^)

-game over-

Thanks for reading another action-packed installment of Design a Day. For background on the Design A Day challenge, take a peek here and here.