Help for the Game of Hijack

Welcome to the network Hijack server. The challenge command is described here. Other commands are the same as for all pbmserv games.

hijack challenge [-size=number] [-num_pieces=number] [-in_place] [-block_marker] userid1 userid2 [userid3]

starts a new game for two or three players.

The -size parameter sets the size of the board (default is 3 tiles per side).
The -num_pieces parameter sets the number of pieces that each player starts with (default is 12).
The -can_rotate option allows cells to rotate after moving.
The -in_place option allows cells to rotate in-place without moving (only applies if -can_rotate is also used).
The -block_marker option specifies that markers cannot move through intervening cells unless their corresponding slots are empty.

Introduction

Hijack is an abstract board game of all-out attack in which players may use enemy pieces against themselves. It is somewhat perverse in that the best way to defend a piece is often to double the threat against it.

Rules

The board is made up of hexagonal cells, each with a slot on each edge indicating a direction of travel. The slots are numbered 0..5, as shown:

`     +-----+              +-----+           0 = up    /   .   \            /   0   \          1 = up right   / .     . \          / 5     1 \         2 = down right  +           +        +           +        3 = down   \ .     . /          \ 4     2 /         4 = down left    \   .   /            \   3   /          5 = up left     +-----+              +-----+   `

The board is a hexagonal arrangement of such cells (3 per side) which are initially empty. Each player starts with 12 markers of their colour in hand.

`                      +-----+                               On   In                     /   .   \                       O: 12 ( 0 + 12 )                    / .     . \                      X: 12 ( 0 + 12 )             +-----+     c     +-----+            /   .   \ .     . /   .   \           / .     . \   .   / .     . \    +-----+     b     +-----+     g     +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / .     . \   .   / .     . \   .   / .     . \ +     a     +-----+     f     +-----+     l     +  \ .     . /   .   \ .     . /   .   \ .     . /   \   .   / .     . \   .   / .     . \   .   /    +-----+     e     +-----+     k     +-----+          +-----+   /   .   \ .     . /   .   \ .     . /   .   \        /   0   \  / .     . \   .   / .     . \   .   / .     . \      / 5     1 \ +     d     +-----+     j     +-----+     p     +    +           +  \ .     . /   .   \ .     . /   .   \ .     . /      \ 4     2 /   \   .   / .     . \   .   / .     . \   .   /        \   3   /    +-----+     i     +-----+     o     +-----+          +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / .     . \   .   / .     . \   .   / .     . \ +     h     +-----+     n     +-----+     s     +  \ .     . /   .   \ .     . /   .   \ .     . /   \   .   / .     . \   .   / .     . \   .   /    +-----+     m     +-----+     r     +-----+           \ .     . /   .   \ .     . /            \   .   / .     . \   .   /             +-----+     q     +-----+                    \ .     . /                     \   .   /                      +-----+`

The scores at the top right of the board indicate each player's total number of markers, which is the sum of their markers on the board (On) plus their remaining markers in hand (In). The numbered cell on the right indicates direction numbers for quick reference.

Play: Each turn the current player must move either a marker or a cell.

Marker move: The player can add a marker of their colour to any empty slot of any cell, provided that they still have markers in hand.

Alternatively, the player can move a marker of their colour to any empty slot on its current cell or any other cell in its direction of travel.

Cell move: The player can move a cell in any direction indicated by any of its markers (of either colour) by moving all of its markers to the new cell location, as if the cell and all of its contents had been picked up and moved. The cell can move any number of steps provided that all intervening cells are empty. Any markers on the destination cell (of either colour) are captured and removed from the game.

Aim: Any player with only 1 marker remaining is removed from the game; the last remaining player wins.

Examples

Consider the following board position with X leading in piece count and O to move:

`                      +-----+                               On   In                     /   .   \                       O:  4 ( 3 + 1 )                    / .     . \                      X:  6 ( 6 + 0 )             +-----+     c     +-----+            /   .   \ .     . /   .   \           / .     . \   .   / .     . \    +-----+     b     +-----+     g     +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / .     . \   .   / .     . \   .   / .     . \ +     a     +-----+     f     +-----+     l     +  \ .     . /   .   \ O     . /   .   \ .     . /   \   X   / .     . \   .   / .     X \   .   /    +-----+     e     +-----+     k     +-----+          +-----+   /   .   \ .     . /   X   \ .     . /   .   \        /   0   \  / .     . \   .   / .     . \   .   / .     . \      / 5     1 \ +     d     +-----+     j     +-----+     p     +    +           +  \ .     . /   .   \ O     X /   .   \ .     . /      \ 4     2 /   \   .   / .     . \   X   / .     . \   .   /        \   3   /    +-----+     i     +-----+     o     +-----+          +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / X     O \   .   / .     . \   .   / .     . \ +     h     +-----+     n     +-----+     s     +  \ .     . /   .   \ .     . /   .   \ .     . /   \   .   / .     . \   .   / .     . \   .   /    +-----+     m     +-----+     r     +-----+           \ .     . /   .   \ .     . /            \   .   / .     . \   .   /             +-----+     q     +-----+                    \ .     . /                     \   .   /                      +-----+`

O has one remaining marker in hand, but instead of adding it they decide to save their h1 marker which is under threat from cells a and j. O could move the h1 marker to any empty slot on cells h, i, j, k or l. However, a much better option is to move the entire cell h to j as shown below:

`                      +-----+                               On   In                     /   .   \                       O:  3 ( 2 + 1 )                    / .     . \                      X:  3 ( 3 + 0 )             +-----+     c     +-----+            /   .   \ .     . /   .   \           / .     . \   .   / .     . \    +-----+     b     +-----+     g     +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / .     . \   .   / .     . \   .   / .     . \ +     a     +-----+     f     +-----+     l     +  \ .     . /   .   \ O     . /   .   \ .     . /   \   X   / .     . \   .   / .     X \   .   /    +-----+     e     +-----+     k     +-----+          +-----+   /   .   \ .     . /   .   \ .     . /   .   \        /   0   \  / .     . \   .   / X     O \   .   / .     . \      / 5     1 \ +     d     +-----+     j     +-----+     p     +    +           +  \ .     . /   .   \ .     . /   .   \ .     . /      \ 4     2 /   \   .   / .     . \   .   / .     . \   .   /        \   3   /    +-----+     i     +-----+     o     +-----+          +-----+   /   .   \ .     . /   .   \ .     . /   .   \  / .     . \   .   / .     . \   .   / .     . \ +     h     +-----+     n     +-----+     s     +  \ .     . /   .   \ .     . /   .   \ .     . /   \   .   / .     . \   .   / .     . \   .   /    +-----+     m     +-----+     r     +-----+           \ .     . /   .   \ .     . /            \   .   / .     . \   .   /             +-----+     q     +-----+                    \ .     . /                     \   .   /                      +-----+`

This move captures three X pieces and unfortunately one O piece (although this is a sacrifice worth making) and forks cells a and k. X is now in a bad position, and must lose at least one piece next turn. X might think of moving cell j to e in the hope that O captures it next turn from f (in which case O would also capture one of their own pieces) but O would probably just capture cell a from this position instead.

Notes

Players may capture their own markers.

Markers cannot be used to directly defend friendly cells, as the opponent can hijack them to capture the pieces they were meant to protect. Hijack is therefore a game of all-out attack. However, an indirect form of defense can be achieved by counterattacking either the attacking pieces or the pieces they attack.

For instance, the formation below shows X attacking an O marker (left). O can defend their marker next move by playing at either slot a1 or slot d4 (right). A move at a1 would threaten the X marker whether it captures or not, so is probably the better option. A move at d4 would threaten the X marker only if it captures the O on cell c; X would probably not use d4 to capture the O on cell c as it would then directly threaten the original X marker on b next turn.

```                                +-----+                                +-----+
/   .   \                              /   .   \
/ .     . \                            / .     . \
+-----+     d     +                    +-----+     d     +
/   O   \ .     . /                    /   O   \ 4     . /
/ .     . \   .   /                    / .     . \   .   /
+-----+     c     +-----+              +-----+     c     +-----+             /   .   \ .     . /                    /   .   \ .     . /            / .     X \   .   /                    / .     X \   .   /     +-----+     b     +-----+              +-----+     b     +-----+       /   .   \ .     . /                    /   .   \ .     . /    / .     . \   .   /                    / .     1 \   .   /    +     a     +-----+                    +     a     +-----+
\ .     . /                            \ .     . /    \   .   /                              \   .   /     +-----+                                +-----+
```

Use the "-can_rotate" option to allow cells to be optionally rotated after being moved. This allows powerful moves that make it hard to capture pieces, especially in the end game, so is not recommended. Use the "-in_place" option to allow cells to rotate without moving. This can also be useful but could lead to stalemates if players rotate - unrotate - rotate - unrotate etc.

Three-Player Version

Three-player Hijack is played as per standard game, however the ability to exploit enemy markers introduces an intriguing complication. Consider the following sequence of play:
B: Adds piece 'b' to threaten 'a'.
C: Captures 'a' with 'b'.

Players can manipulate the next player into performing their captures for them - or at least try to, as the next player will not necessarily make the capture that they would prefer. This can lead to some interesting exchanges.

Syntax

The move syntax is "hijack move <board#> <userid> <password> <move>" where "<move>" may be of the format:
"a5" = Add a marker at a5.
"a1-b" = Move marker a1 to b1.
"a1-4" = Move marker a1 to a4.
"a1-b4" = Move marker a1 to b4.
"a-b" = Move cell a to b.
"a-b++" = Move cell a to b then rotate it twice clockwise
(only if the "-can_rotate" option is used).
"a-" = Rotate cell a once anticlockwise without moving
(only if the "-can_rotate" and "-in_place" options are used).

History

Hijack rules copyright (c) Cameron Browne, May 2007.

The name Hijack refers to the fact that players can effectively hijack cells by exploiting enemy markers to help capture other enemy markers.

Players are encouraged to yell out "Hijack!" when exploiting enemy markers. This is a great game for passing the time on long international flights.

Implementation and Help file by Cameron Browne, May 2007.