From: dbush@csugrad.cs.vt.edu (David Bush)
Newsgroups: rec.games.abstract
Subject: A small TwixT game
Summary: An annotated game on a 12x12 board, and some generalities.
Keywords: twixt
Date: 19 Nov 92 02:24:07 GMT
Organization: Virginia Tech Computer Science Dept, Blacksburg, VA

Here's a sample "game" I made up on a 12x12 TwixT board:

                       RED

        A   B   C   D   E   F   G   H   I   J   K   L
    1       .   .   .   .   .   .   .   .   .   .

    2   .   R8  .   .   .   .   .   .   .   .   .   .
             \
    3   .   . \ B7  .   .   .   .   .   .   .   .   .
               \ ~~---__
    4   .   .   R3  .   B6  .   B2  .   .   .   .   .
B                \               \                          B
L   5   .   .   . \ .   .   .   . \ .   .   .   .   .       L
A                  \               \                        A
C   6   .   .   .   R7  .   .   R1  B5  .   .   .   .       C
K                  /     __---~/   /                        K
    7   .   .   . / .   R4  . / . / .   .   .   .   .
                 /_---~~     /   /
    8   .   B3  R2  .   .   R6  B1  .   .   .   .   .
             ~~---__         \
    9   .   .   .   B4  .   . \ .   .   .   .   .   .
                               \
   10   .   .   .   .   .   .   R5  .   .   .   .   .

   11   .   .   .   .   .   .   .   .   .   .   .   .

   12       .   .   .   .   .   .   .   .   .   .

                       RED

  RED  BLACK
1. G6             A solid opening move. By playing midway between the red
               borders, red is making black's task as difficult as possible.
1.      G8      On a larger board, this might be too close to the red peg,
               but black's game is already desperate. Black might have tried
               G10 instead, after which 2.E9,G4;3.E5(linking G6),D9;
               4.C8(linking E9),E11(G10,D9);5.B10(C8),D3;6.D2 (red wins) is
               one possible continuation.
2. C8            Red gets in black's face. Playing 4 holes away from your
               opponent's peg like this is frequently a good blocking move
               to make, particularly when the move is supported by a nearby
               peg as it is here.
2.      G4       Black follows the opening maxim: "Don't start a fistfight
                too soon." Simply playing E7 loses to 3.D6(C8),D5(E7);
                4.C4(D6) and red will win the race to the wall. Note that
                in this variation, red's G6 peg is not part of the final
                bridge. It's perfectly okay to abandon pegs this way.
                 Black might have played F4, after which one continuation is
               3.E5(G6),D5(F4);4.C6(E5) and red is unstoppable.
3.C4             The C4-C8 pegs form what is called a "setup," which means
               they threaten to link together in one move in two different
               ways. C4-G6 also threatens to link in one move, but they can
                only link via E5, so this is not a setup.
3.      B8     Black tries to make two threats at once. Now we're in the
              middle game (things move along quickly on a quarter board.)
4.E7          (linking G6,C8): the best move. Red covers both threats at
              once. If for example red had played D6(C4,C8) then
              4. ... D9(B8);5.G10,E7(G8,D9);6.H8(G6,G10),F6(G4,G8) and black
              has a win. Or if 4.E9(C8),D7(B8);5.E7(C8,G6),F6(G4,D7).
4.      D9    (linking B8): the only move, not that it matters.
5.G10         Now it's red's turn to make two threats at once.
5.      H6    (link G4,G8)  Black is just going through the motions.
6.F8          (link G10,G6) E9 was also possible.
6.     E4
7.D6(C4,C8),C3(E4);
8.B2(C4)             Black resigns.

Here are some pithy aphorisms about the game:

* Sometimes the best offense is a good defense. See red's move #2 above.
  By falling back to block, red tries to have a "net" built by the time
  black gets there.

* In the opening, keep the whole board in mind. Don't get drawn into a
  local battle if a distant move would help your position more. Remember
  just because you put some pegs down doesn't mean they have to be part
  of your final bridge.

* Develop an eye for the "diagonals"- for example in the game above, the line
  B2-C4-D6... was very important for red. In a "race" such as in the analysis
  to black's 2nd move, being at least on such a crucial diagonal means you will
  win the race to the wall.

HANDICAPS AND EQUALIZATION

 As the above game demonstrates, red has a powerful initiative. Between strong
players of equal strength, this may mean that red will win more often than not.
Here's a ritual the players can go through that is intended to equalize the
game- make it more balanced. On an otherwise empty board, one player puts down
two red pegs (which might be linked) and one black peg, producing a position
with black to move. The other player then decides which side to play. Play then
proceeds from this position. The red pegs should be placed less than ideally
(although not abysmally), whereas black's peg is well placed, producing a
position that is as close to even as the "placer" can make it.

 On the other hand, it is more likely that there will be a considerable
disparity between the players. In order to compensate, here's a possible way
to handicap the game: reduce the width of the playing field, so that black (the
weaker player) has less distance to bridge than red. With an actual game set,
this might be accomplished with a black rubber band of the right size. A "half
board" game (12x24) is a pretty severe handicap. Reducing black's distance from
24 to 23, on the other hand, just might serve to balance out red's first-move
initiative! I have no idea if this is true. If it is, that would render my
proposed "placer-chooser" ritual unnecessary.

David Bush        Virginia Tech, Blacksburg, VA    dbush@csugrad.cs.vt.edu