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Star Trek 3D Chess Rules

Star Trek 3-D Chess Rules

Charles Roth, 8 October 2010       (Techblog top)

I. Introduction
I recently bought the instructions for building your own Star Trek 3D chess set, and my 10-year-old daughter Emma and I proceeded to build it from scratch (which was a lot of fun all by itself).  While the booklet had great construction details, I admit I had to puzzle over the description of the rules for a while.  There were also a few ambiguities in the booklet that were cleared up on the web site (linked to above).

So I thought it would be an interesting challenge to write a clear and concise description of the rules...

II. The Rules ("Federation Revised Standard")

  1. Board layout.  The image at the top-right shows the full board in perspective.  There are 3 "main" boards (4x4 squares each), and 4 "attack" boards (2x2 each).  The main boards are fixed, but the attack boards can move(!).  More on that later.

    The "flattened" diagram to the right shows a view of the board at the start of a game, looking down from above, with some main boards partially overlapping each other.  Each square is uniquely identified by

    1. its file (the letters a thru f)
    2. its rank (the numbers 0 thru 9)
    3. its elevation or z-level (the numbers 1 thru 7)

    The main boards are, starting from the bottom, elevations 2, 4, and 6.  The attack boards in their starting position are at elevation 3 and 7.  I'll use these square notations to show specific examples of how pieces move.

  2. Starting position.  Shown below.  The white Bishops and Knights are at elevation 2 on the low main board, and the King, Queen, and Rooks are at elevation 3 on the attack boards.  Note that the King and Queen pawns are directly over the Knights.  (Well, just slightly off of directly over, due to the way the board is designed.)

    The black pieces have the equivalent starting position on the high main board and attack boards, but mirrored, so that each side's Queen is, as in normal chess, on it's own color.

  3. Moves on the main boards.  Moving across the main boards is like normal chess, but with an option to change levels.  Look "down" at the stack of boards, and imagine that you are moving a piece in its normal style across the board(s).  The important difference is that you may choose to end the move on a different level (any different level) than you started. 

    For example, assume we have a completely empty board, with just one Rook were at c1(2), meaning file c, rank 1, elevation 2.  It could move to any of:

    • c2(2), c3(2), c4(2)
    • c3(4), c4(4), c5(4), c6(4)
    • c5(6), c6(6), c7(6), c8(6)

    The square you want to move to is called the target square.  The rule for moving a piece is this:

    1. There is one and only one path it can take from the starting square to the target square...
    2. ...which must be the highest possible path of squares...
    3. ...that are not above the higher of the start or target squares.

    That's a mouthful.  But we can break the rule down into three simple cases:

    1. If the start and target squares are on the same level (same elevation), then the path just stays on the squares on the same level, like normal chess.  (If there are other pieces in the way on that level, then you just can't get to your target square.)
    2. If the target square is higher than the starting square (i.e. you're moving up), then you must take the highest possible path that does not go above the target square level.  That is, you can't zig-zag, meaning go up higher and come back down again.  (If there are other pieces along that highest path, then you just can't get there.)
    3. If the starting square is higher than the target square (i.e. you're moving down), then you must take the highest possible path that does not go above the starting square.  (Ditto about blocking pieces.)

    This sounds complicated, but put just a couple of pieces on the board and try it out, and it will become clear.  Just remember -- "highest path, no zig-zagging".

  4. Moves on the attack boards.  The attack boards make things more... interesting.  They break the previous rule... a little bit.

    When an attack board is mounted above (or below -- more later) a main board, the squares on the attack board are allowed to be an alternate route to the matching (directly above or below) squares on that main board.

    An example will make this clearer. 

    • Imagine a poor, solitary white King on it's initial square at e0(3).
    • Now put a black Rook at e4(2).
    • The Rook has the King in check... and it can attack thru either square e1(2) or e1(3).
    • If you put a white Pawn at e1(2), the King is still in check.  You must block both e1(2) and e1(3) to save the King.

    Or turn it around the other way... imagine a white Rook at b0(3).  It can attack a black Bishop at b3(4), even though it zig-zags down to b1(2) and then goes back up to get to b3(4).  It's as if the attack board square at b0(3) were really at b0(2), even though that square doesn't actually exist.

    In Star Trek terms, we might call this a "quantum superposition" of the attack and main board squares, or maybe a (very tiny) set of parallel universes.

  5. Pawn Promotion.  This is an easy one.  White Pawns promote (normally) whenever they reach rank 8 or rank 9.  Similarly, black Pawns promote whenever they reach rank 1 or rank 0.

  6. Moving the Attack boards.  Yes, the attack boards can move.  The white player initially owns the attack boards at (mounted in the corner of) squares b1(2) and e1(2).  The black player owns the other two.

    On their turn, a player may, instead of moving a piece, move one of their attack boards.  The board must be empty, or contain only one of their own pawns.

    1. The board may invert.  This means flip to the opposite post on the same square, turning the board upside down.  (If it was mounted above a main board, now it "hangs" below that same board.)  Or...
    2. The board may move 1 or 2 squares to another post, or
    3. The board may move 1 or 2 squares to another post and invert.

    Moving an attack board that is "piloted" by a single pawn can be a very fast way to advance a pawn to promotion.  It can also open an alternate path to a piece that was blocked by squares on a main board.

  7. Capturing Attack boards.  If the black player captures the last (only) white piece on one of white's attack boards, that board now belongs to black, and may be moved by black in the normal way.  And vice-versa for white.

    A board with no pieces on it is safe and cannot be captured.

  8. Castling.  The King and the Rook in question may not have previously moved.  The King must not be in check on either its original or destination square.
    • King-side.  The King may switch places with its Rook. 
    • Queen-side.  If the Queen has moved out of the way from its original square on the b file, then the King "teleports" to the Queen's home square, and Queen's Rook teleports to the King's home square.

    King-side castling in particular is a good way to move a Rook into play.

  9. Special pawn moves.  All special pawn moves (first move option to move 2 squares, and "en passant" captures) play out normally.  It can be tricky to remember, however, that a pawn that started at (say) b1(3) and moved to b2(2) cannot then move directly to b4(2), since it has already taken its first move.

  10. Rook Pawn option.  A standard (but optional) rule handles the case of the "stuck" Rook Pawn (e.g. at a1(3), or anywhere on the a or f files).  The darn thing can't normally go anywhere, unless the opponent is dumb enough to place a piece on the diagonal (e.g. b2(2)), or if the whole attack board moves.

    So the standard-but-optional move allows (only!) pawns on the a or f files to (also!) move inwards one or two (if 1st move) squares, or to attack diagonally inwards.  Once the pawn is anywhere on the b thru e files, it behaves normally.

III. Thoughts on game play.

  1. The best way to play the game is to put it on the floor and look down.  This makes it much easier to see "through" the boards and see which squares are directly above and below which.  Remember that the squares line up by color, i.e. a red square is always directly above or below another red square.

    Spock and Kirk may have played looking sideways along the board, but they were, after all, just acting...

  2. Bishops seem less powerful than in normal chess, and Rooks and Queens are probably more powerful.  Center control seems to matter less than opening up long files to attack along.

  3. Pawns are often a nuisance, at least early in the game.  But watch out for those warp-speed "piloted by a pawn" attack boards!

  4. Have fun, and forgive your opponent's easy/obvious mistakes while you're both learning.  Live long and prosper!