NAME: Stack Chess

TYPE: Chess variant - standard board, standard piece types

DESCRIPTION: Knowledge of how to play chess is suggested/required. This variant of Chess uses Icehouse (http://www.wunderland.com/icehouse/Icehouse.html) pieces. The pyramids (the Icehouse pieces are small hollow-bottomed pyramids) are placed in stacks. A stack of a given size represents a specific chess pieces. Stacks are created and split apart in the course of play.

RULES:
Definitions and Background- The pyramids are size 1 (smallest) to size 3 (largest). There are 5 pyramids of each size for each person. A stack is one or more pyramids stacked on top of each other on a single space, with all pyramids higher in a stack being smaller than or equal to all pryamids lower in that stack. The size of a stack is the sum of the sizes of the pyramids in the stack. A stack of a given size corresponds to a specific chess piece:

stack size	chess piece
1	pawn
2	knight
3	bishop
4	rook
5	king
6	queen
>6	not allowed

The notation for stacks is the chess piece symbol and a comma seperated list of the pyramids that make up the stack, from bottom up (largest to smallest). E.g. A rook made of a size two and two size ones would be R[2,1,1].

Setup- There are not enough pyramids to make a full compliment of chess pieces, so the board is a bit sparser a the beginning. The set up is:

     |--------|
     |R BQKBN |   With initial pieces being
    2| #ppppp#|   p - p[1]   - a pawn
     |# # # # |   N - N[2]   - a knight
     | # # # #|   B - B[3]   - a bishop
     |# # # # |	  R - R[2,2] - a rook
     | # # # #|	  Q - Q[3,3] - a queen
    2|#ppppp# |	  K - K[3,2] - a king
     | NBQKB R|	  2 - an extra size 2 pyramid on the side 
     |--------|       (may be used for promotion)

Play- Each turn you make one move. A move is ONE of

• Basic movement: Any stack moves and captures as the appropriate chess piece.
• Creating new stacks: If a stack can move in such a way that it can land on another one of your stacks, you may combine those two stacks, PROVIDED:
  • The size of the resulting stack does not exceed 6
  • The bottom of the stack being moved is smaller than or equal to the stack on which it is landing.
  Once joined, the new stack is considered a single unit of the appropriate type.
• Splitting stacks: If a stack contains more than one pyramid, you may move any number of pyramids OFF THE TOP of that stack as a single new stack (e.g. with an R[2,1,1] you could move off a p[1] or an N[1,1] in a single move, but NOT a p[1] and another p[1] in the same turn). The sub-stack moved away moves as the piece that sub-stack represents. Once split, the two resulting stacks (the one in the starting space and the one split off the top) are completely independent units.

• Kings: If a move does not leave you with at least one unchecked king at the end of your turn, then it is not a legal move.
• Checking: Kings are put into Check as normal. However, when a player's king is in Check, they may decline to protect/save that king AS LONG AS they control at least one un-Checked king by the end of their turn.
• Pawn Promotion: When a Pawn stack (i.e. single size 1 pyramid) moves into an empty space in the 8th rank, you may take a single pyramid (of any size) that is not currently on the board (i.e. was captured or never placed to begin with) of your color and place it under that pawn (thus creating a larger stack). SO, you may not promote pawn unless you have a pyramid available to put under it (i.e. the initial spare 2, or one or more of your pieces captured). NOTE: the highest a pawn can get in a promotion is a rook (p[1] -> R[3,1]).
• Winning: You when when you have check mated all your opponents kings. Conversely, you lose when you have no un-checkmated kings by the end of your turn.

VARIATIONS:

• Pieces stack if they can 'capture' the piece that are stacking onto, not move on to it. I.e. normally a pawn would be able to stack onto a piece directly in front of it but not diagonally in front of it; with this variation a pawn can stack on a piece diagonally infront of it, but not directly in front of it. Pieces other than pawns aren't affected by this rule change since they all move and capture with the same action.
• Any stack of 6 or more counts as a queen.
• A stack of 7 (not 5) counts as a king (A stack of 5 would be a new kind of piece).
• Get multiple Icehouse sets and play with a full set of chess pieces.
• Pawns do NOT get double move from their starting rank (the game ges intersting enough quickly enough anyway)

COMMENTS: It's wacky. Some strategy considerations:

• Pawns are key; you can get them towards the back rank pretty quickly and then keep them there to bring back captured pyramids. Plus, you only have five of them.
• There are really fascinating new 'discovered check' possibilities.
• The rook that splits to mutually protecting knights and the queen that splits to mutually protecting bishops is pretty cool.
• A distantly made second King can suddenly free up your first King to split, and therefore makes a very tricky discovered threat.