[ortzuncp] Crazyhouse Annihilation

We present a chess variant based on Crazyhouse, but with the following rule modifications.

We'll use the term piece to mean piece or pawn.

The game is played until annihilation, that is, the losing player has no pieces left on the board.

The king is not a special piece.

Castling is prohibited.

Drops may only happen on empty squares attacked by one of your pieces.  Therefore it is possible (probably likely) that at the end of the game, the losing player still has pieces in hand, just nowhere to drop them.

A player may pass instead of making a move.

Stalemate is not an end of game situation: the stalemated player is simply forced to pass.

Mutual stalemate and repetition, including consecutive passes, are draws.  I predict extremely rare.

Like Chess960, the first and eighth ranks are scrambled before the game.  Unlike Chess960, both sides are scrambled independently (not necessarily mirror).  Drops make opposite colored bishops unnecessary, and no castling obviates the need for the king between rooks.  There are 8!/2/2/2=5040 permutations per side, so 25401600 total initial positions.  That should be sufficient to prevent death by opening theory.

After seeing the initial position, one player chooses the side to play, the other player chooses who moves first (typically oneself).  The board is rearranged if necessary so white moves first.

The inspiration was looking at chess endgames.  They are wonderful "deep" puzzles, but the flavor of an endgame is very different from the rest of the game, with zugzwang playing an important role.  The goal of this game was to maintain the feel of military strategy through the whole game.

Although greater power (more pieces) generally defeats lesser, I am curious if tactics can effect dramatic turnarounds. If not, we propose one more rule: a square does not have to be empty to accept a drop. That is, an attacked opponent's piece may be captured with a drop directly onto it. This permits a piece to simultaneously capture, be defended, and attack more, allowing for more powerful tactics, though lessening the power of the pin.

Also consider the chess/go 囲碁 hybrid Gess played with these rules.