By Ralph BetzaIn the 1970s I invented Cassandra Chess, but merely presented the central idea without attempting to make a playable game out of it; recently I was reminded of Cassandra Chess, and found it sufficiently intriguing that I decided to complete the game.
Prophecies of DoomA prophecy of doom specifies that a particular enemy piece type will be on a specified square some specific number of moves in the future. If the prophecy comes true, the targeted piece is removed from the board.
For example, suppose that each player is allowed to make a prophecy each turn, targeting any piece type, and always two moves in the future.
- White plays 1. f2-f4, prophecying Ke8; this means that when White is ready to play his third move, if there is a Black Ke8 it will be removed from the board.
- Black replies 1...e7-e5, prophecying Ke1.
- White plays 2. g2-g4, prophecying Ke7.
- Black plays 2...Qd8-h4 checkmate, and because the game ends instantly his Ke8 is not removed.
Rules of Cassandra Chess
- White may make no prophecy on his first move.
- All prophecies are aimed two moves in the future.
- Each player may have no more than one outstanding unfulfilled prophecy. In other words, if you make a prophecy on move 1, then on move 2 you may not make another because you have one pending, but on move 3 you will be free to try again.
At the beginning of the game, one may make prophecies only
about Pawns. Once a player has a successful prophecy about Pawns
(or if the foe no longer has any Pawns),
that player may then target Knights (or
and may no longer target Pawns.
The target of one's prophecies thus advances through the ranks from Pawns to Knights to Bishops to Rooks to Queen to King. A successful prophecy about a King would of course end the game.
- White may make no prophecy on his first move in order to balance the initiative of the first move.
All prophecies are aimed two moves in the future, but if you like
the game you are encouraged to try it with different degrees
"Two moves" was chosen as the shortest playable length, which works well in combination with the rule limiting you to one pending prophecy.
Each player may have no more than one outstanding unfulfilled
prophecy, and therefore it will sometimes be a good idea to
not make a prophecy in order to be free to do so next turn.
Note that if you play, for example, allowing any number of pending prophecies at once and also allowing prophecies from 4 to ten moves in the future, it will be difficult to keep track of all the outstanding prophecies and difficult to calculate your moves.
I chose "two moves" and "one pending" in order to make the game easier to play and enjoy.
The advancing target is the key to playability, and also has
some tactical implications. At the start of the game, one can
save one's Pawns for a long time, but at the cost of development;
at some point you must decide that giving your opponent a step up
to Knights is less bad than continuing to move nothing but Pawns.
The absence of a piece type gives a free advance to the next type; this not only can affect decisions about what to trade, but it also makes sure that prophecies can be made until the end of the game, for example, even in an endgame with nothing but Kings and Pawns there is something new and interesting in Cassandra Chess.
When your target advances, the old target becomes immune. Otherwise you would run out of Pawns before the endgame.
Different ArmiesThe game works perfectly well with different armies.
When an army has an unusual balance, as for example the Colorbound Clobberers have, one might argue that one side or the other gains an advantage. This argument should be discussed on the board.
Written by Ralph Betza.
WWW page created: January 14th, 2003.