Rules for Trellis

Trellis is a connection game played on a checkered board.

More details about Trellis including the complete official rules can be found at http://home.fuse.net/swmeyers/trellis.htm

Implementation by Cameron Browne, March 2003.

Object of the game:

The vertical player (V) aims to connect the top and bottom edges of the board with a chain of V pieces, while the horizontal player (H) aims to connect the left and right sides of the board with a chain of H pieces.

Board layout:

Below is a standard 15x15 game won by Vert, who has completed a chain of their pieces from top to bottom.

   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O

15  --- --- --- --- ---V--- --- --- --- --- --- --- --- ---  15
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
14  --- --- --- --- ---V--- --- --- --- --- --- --- --- ---  14
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
13  --- --- --- --- --- ---V--- --- ---V---V--- --- --- ---  13
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
12  --- --- --- --- --- ---V---V---V--- --- ---V--- --- ---  12
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
11  --- --- --- --- --- --- --- --- --- --- ---V --- --- ---  11
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
10  --- --- --- --- --- --- --- --- --- --- ---V--- --- ---  10
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
 9  --- --- --- --- --- --- --- --- --- --- ---V--- --- ---  9
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
 8  --- --- --- --- --- --- --- --- --- ---V--- --- --- ---  8
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
 7 H---H---H---H---H---H---H---H---H---V--- --- --- --- ---  7
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
 6  --- --- --- --- --- --- --- ---V---H---H---H---H---H---H 6
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
 5  --- --- --- --- --- --- --- ---V--- --- --- --- --- ---  5
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
 4  --- --- --- --- --- --- --- ---V--- --- --- --- --- ---  4
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
 3  --- --- --- --- --- --- --- ---V--- --- --- --- --- ---  3
   | : | - | : | - | : | - | : | - | : | - | : | - | : | - |
 2  --- --- --- --- --- --- --- ---V--- --- --- --- --- ---  2
   | - | : | - | : | - | : | - | : | - | : | - | : | - | : |
 1  --- --- --- --- --- --- --- ---V--- --- --- --- --- ---  1

   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O

Note that dark squares (denoted by ':') belong to Vert and light squares (denoted by '-') belong to Horz. Connections follow orthogonally adjacent lines between points ('|' and '---') as well as conditional connections: each player connects diagonally across their squares.

Horz has not won in the above example because their connection is broken at I7-J6 where it crosses a Vert square. No diagonal connection exists for Horz across this square but a diagonal connection does exist for Vert, giving Vert the win.

Movement:

One or two pieces can be placed on empty board points per turn, provided that if two pieces are played then they are three points apart (either a knight's move from each other or in a line). For instance, if Vert plays V (below) they can then place a second piece at any of the points marked x.