Tank Chess

Tank Chess

      a   b   c   d   e   f   g   h
    +---+---+---+---+---+---+---+---+
  8 |*M*|*N*|*B*|*A*|*K*|*B*|*N*|*T*|  8    Black
    +---+---+---+---+---+---+---+---+
  7 |*P*|*P*|*P*|*P*|*P*|*P*|*P*|*P*|  7
    +---+---+---+---+---+---+---+---+
  6 |   |:::|   |:::|   |:::|   |:::|  6
    +---+---+---+---+---+---+---+---+
  5 |:::|   |:::|   |:::|   |:::|   |  5
    +---+---+---+---+---+---+---+---+
  4 |   |:::|   |:::|   |:::|   |:::|  4
    +---+---+---+---+---+---+---+---+
  3 |:::|   |:::|   |:::|   |:::|   |  3
    +---+---+---+---+---+---+---+---+
  2 | P |:P:| P |:P:| P |:P:| P |:P:|  2
    +---+---+---+---+---+---+---+---+
  1 |:M:| N |:B:| A |:K:| B |:N:| T |  1    White
    +---+---+---+---+---+---+---+---+
      a   b   c   d   e   f   g   h

The pieces

• The bomb, denoted by M in the above diagram, is represented by a normal standing rook. The bomb moves one kingstep at a time, i.e. one space in any of the eight directions, like a King, but it cannot capture. Instead of moving, it may blow up: the bomb and any pieces within one kingstep from it are removed from the board. The bomb affects nine squares: the square it is on and the eight squares one kingstep away from it. The bombs are at a1 and a8 at the start of the game.
• The atomic bomb, denoted by A in the above diagram, is represented by a normal queen. The atomic bomb is identical in all respects to the bomb, except that it affects two kingsteps: it affects twenty-five squares. However, it still moves one kingstep at a time. The atomic bombs are at d1 and d8 at the start of the game.
• The tank, denoted by T in the above diagram, is represented by an inverted rook. It moves like the bomb, but it cannot blow up and cannot capture. What it can do is to push pieces. No matter how many pieces it has to push, as long as there are pieces of either color standing on the straight line starting at where it moves to, it can push all of them one space. If something at the end is pushed off the board, it is removed from the board and never reenters. For example, White can move d2-d4, d4-d5, e2-e4, f2-f3, and then push everything: h1-g2 pushing g2 to f3, f3 to e4, e4 to d5, and d5 to c6. Since c6 is vacant, the push stops there. However, if black had moved c7-c6, the move h1-g2 also pushes c6 to b7, b7 to a8, and "captures" the black rook at a8. Altogether, there are eight possible push directions. The tanks are at h1 and h8 at the start of the game.

The bombs (of either type) only explode when their owners decide them to, and this uses up a move. In particular, there is no chain reaction when a bomb explodes and takes out another bomb, when a bomb is pushed off the board by a tank, or when the bomb is captured.

The game is played as if it were normal chess, except for the modifications mentioned in this text.

Other rules

1. Pawns pushed to the first rank can move one space forward only. Pawns at the second rank can always move two spaces forward, without the ability to jump. Pawns pushed to the eighth rank promotes as per normal, the pusher (or perhaps this should be the owner) decides its new rank.
2. Pawns may promote, instead of to a knight or a bishop, to a bomb, an atomic bomb, or a tank. There is no normal queens or rooks in this game.
3. There is no castling.
4. If tanks keep pushing each other, declare a draw. This is derived from the three-moves draw rule in normal chess.
5. If one king disappears, either because of a bomb explosion or a tank push, the owner loses. If both kings explode at the same time, the game is a draw.
6. Checks and checkmates are as per normal. Mention check when it is possible to eliminate the opponent's king at the next move. Mention checkmate when it is check and it is impossible for the opponent to parry it.

A sample position

Black can move Me2, checkmate. Because wherever the White King moves to, the Black Bomb will simply explode.

Another sample position

White moves Tf6(Nf6-g7), check. Because after that White can move Tf6-g7, pushing the Black King off the board. This is not a good move, since Kxg7 wins the White Knight.

Play It!