I was regrettably unable, this past weekend, to attend a favorite board gaming get-together. However, I still had the chance to play the classic Twixt. In addition to being just plain fun, Twixt is a great example of how minimal, focused rules can expand an interesting dynamic into a compelling game.

Twixt is an abstract in which two players draw lines across a square board, trying to get from one side to the opposite. Of course, each player’s line tends to block the other’s, and so the players have to jockey for position and set themselves up to extend their lines in multiple directions. The game ends up feeling very much like chess, with players thinking several moves ahead and trying to threaten many lines of advance.

One of the central problems a Twixt player has to solve is that, because both players extend their lines at the same rate, it’s impossible to cut off an opponent whose line is in the lead. Chasing therefore doesn’t work; one must instead find a new spot to play in, in front of the opponent’s line, and build a fresh defensive position.

Fans of abstracts might recognize that situation from another game:

A fundamental part of Go strategy is the “ladder.” The player climbing the ladder (White, in the image above) can never escape by continuing; the other player will counter-move until the ladder reaches the edge of the board and all the pieces in the ladder are captured. Instead, the player in the ladder has to play somewhere else, creating a new threat that might eventually make it possible to free the endangered pieces.

Go enjoys enormous depth, and the ladder is only a basic element of its strategy. Yet, Twixt takes the problem of the ladder and turns it into an entire game in its own right. There is no taking of the opponent’s pieces in Twixt, and unlike chess none of the pieces move in a special fashion. There is only the futility of the chase, of climbing the ladder once behind, and the complex decisions about how to jump forward one has to make as a result.

The primacy of getting out of chases by finding new positions in Twixt strategy is emphasized by how few rules there are. Add one peg to the board each turn; connect the new peg to any other pegs the connecting pieces included with the game can reach. Most questions about whether a move is legal can be answered without resort to the rulebook, since the connecting pieces physically prevent illegal links. The entire ruleset, complete with four-player variant, strategy advice, and a brief sample game, fits on a cardboard sleeve about the size of an A4 sheet of paper. Learning the game takes less than a minute, and from that point on there’s nothing to distract from recognizing that chasing won’t work and thinking about how to respond to that problem.

One might think that that would not be enough–but it is. Twixt is not a trivial game. Blocking an opponent who has gained the lead is difficult. Fooling an opponent with a blocking position into blocking incorrectly so that a line can continue is even more difficult. It has given rise to its own version of chess problems, and is played in tournaments.

Twixt, then, is an object lesson in the power of finding something interesting in a design and then turning the entire game toward that element. In the vast context of Go laddering is a relatively minor player; when put on the stage alone, however, it proves able to carry a show by itself. The result of focusing an entire design on the laddering dynamic is an elegant and fascinating game, one very much in the moments-to-learn-lifetime-to-master category. As someone who hopes to add his own work to the pantheon of easy-to-learn-lifetime-to-master games that Twixt has reached, I won’t forget its example.