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Hex:
A Strategy Guide

Matthew Seymour


Chapter 1

Rules

Hex is a two-player strategy game, in the same vein as Go or chess. In Hex, players compete to form a connection between opposing sides of the game board. Hex’s most appealing aspects are its simple rules and its decisiveness—there are no ties or draws in Hex. Yet despite the simplicity of the rules, the game exhibits surprising strategic depth. This book explains the basics of Hex strategy.

The rules are very simple. The game of Hex is played on a diamond-shaped board of hexagonal tiles (“hexes”) shown in Diagram 1. The board can be of any size. This book is primarily concerned with strategy on the 13×13 board, although I will occasionally use smaller boards in some examples. Two opposing sides (northwest and southeast) are marked black, and the other two (northeast and southwest) are marked white. The four corner tiles belong to both sides.

a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 Reset board to initial state Next move Previous move Last move First move

Diagram 1

The board.

The players, Black and White, take turns placing stones on empty hexes, with Black playing first. These stones are never moved or captured. The object of the game is to connect your two opposing sides with an unbroken chain of adjacent stones. There are no restrictions on this chain; it may twist and turn. Diagram 2 shows a winning connection for Black.

Notice how, with the black player connected, it’s impossible for White to form a connection between her two sides. In fact, Hex can never end in a draw: the only way to win is to connect your two sides, and the only way to prevent your opponent from connecting is to make a connection yourself. And since stones are only added and never removed, the game is guaranteed to end.

a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 Reset board to initial state Next move Previous move Last move First move

Diagram 2

A winning connection for Black.

1.1 The swap rule

There’s just one more rule. The rules stated above give too large an advantage to the first player, Black. To counter this, the swap rule is used. This rule is only in effect after the first move of the game. The idea is to give the second player the choice to take or “swap” the first player’s move, if they feel it’s too strong. There are a few ways to state this rule, perhaps the simplest is:

Swap Rule
After the first move of the game (a black stone), the second player has the choice of which colour she wishes to play. She may choose to play the white stones as normal, or “swap” colours and play with the black stones. Regardless of what the second player chooses, whoever has white plays the next move, and play continues as normal alternating between the players.

So if the first move is too strong, the second player can take it by choosing the black stones, while if it is weak, the second player can pick the white stones and move next themselves. The incentive for the first player is to play as fair a move as possible, thus ensuring an even game.

Another formulation of the swap rule avoids having the players change colours, although it’s a little more complicated:

Swap Rule
After the first move is made by Black, White may choose to play as normal, or to swap. If White swaps, the stone’s colour is swapped from black to white, and the row and column are interchanged. Play proceeds with Black.

It’s probably easiest to see this in an example. If the opening play is on b5 (fifth row, second column, see 1.2 Notation below) then White may choose to swap it to e2 (second row, fifth column), as in Diagram 3. e2 is White’s equivalent of Black’s b5. Note: sometimes to save space I will only show a portion of the board as in Diagram 3.

Both versions of the swap rule are equivalent. The option to swap is only available immediately after the first move of the game.

a b c d e f g h 1 2 3 4 5 6 7 8 Reset board to initial state Next move Previous move Last move First move
a b c d e f g h 1 2 3 4 5 6 7 8 Reset board to initial state Next move Previous move Last move First move

Diagram 3

The effect of swapping.

1.2 Notation

Hexes on the board are referred to by their row and column. The column is indicated first with a letter (a, b, c, …), followed by a number indicating the row. Diagram 4 shows a few examples of how to read board coordinates.

d5 f9 k12 a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 Reset board to initial state Next move Previous move Last move First move

Diagram 4

Reading board coordinates.

Since stones never move in Hex, games are rather easy to notate: we simply place the move number on the stone. So the opening sequence of moves a3 d8 g7 c3 would be notated as in Diagram 5. Note: you can click on the moves in the text to see them on the diagram.

1 4 3 2 a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 Reset board to initial state Next move Previous move Last move First move

Diagram 5

The main complication is the swap rule. For that I’ll just put an “S” to indicate the swapped stone, and then the moves continue with move 3. So the opening m8 S swap k10 k11 j11 would look like Diagram 6 (since m8 swaps to h13).

1 3 5 4 S a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 Reset board to initial state Next move Previous move Last move First move

Diagram 6

1.3 Using the interactive diagrams

All the diagrams in this book are interactive. You can click on an empty hex on the board to make a move (try this out on the digrams in the previous section to see what I mean). The board “remembers” the full sequence of moves played on it, in addition to any numbered moves that it started with. You can use the and buttons to move forward or back one move in the sequence. You can use the and buttons to move to the end or the beginning of the sequence. Use the button to reset the board to its initial state. When you see a sequence of moves referenced in the text, you can click on the moves in the text to set the board to that point in the sequence. This helps prevents distractions from moves that come after that move. This feature can be helpful when there is a paragraph referencing a diagram with a large number of moves on it. As you read through the text, click on the moves to keep the board state in line with the discussion.

I strongly encourage you to try out variations and ideas you have as you read the book. If a concept I mention is not entirely clear to you, see if you can figure it out by playing around on the associated diagram. Once you’re done trying out variations be sure to hit the button when you continue reading to ensure that the board matches the text (if the button is visible and not greyed out, it means the board isn’t in it’s initial state).

1.4 Playing the game

Unfortunately physical Hex sets are difficult to come across. The Parker Brothers’ version was published the 1950s; unsurprisingly, it’s difficult to find a copy. Aside from that there are a handful of websites offering sets, although the prices are rather high.

Fortunately you don’t need a board to play Hex! Since stones never move a game can be played with pen and paper. I’ve included printable Hex boards in the appendix. You can print these out and mark your moves on the page with different colour pens. Red and Blue are the traditional colours (for Black and White respectively). Conveniently, if both players write their move numbers down inside each move then the resulting page serves as a complete record of the game played.

Besides pen and paper there are also websites for playing Hex. Most websites where you can play Hex offer it alongside other board games. There are two varieties of online play: “real-time” and “turn-based.” In real-time games players make moves within a few minutes or less. Players will have to remain present until the game is over. In turn-based games players typically have a day or more to make a move. Players typically log in once a day or so and move in all their games. This also allows a player to spend more time analyzing their move if they should choose to.

Turn-based Little Golem is probably the most popular place to play Hex online, and it’s where I typically play. There are a large number of players, and Hex can be played at sizes 11×11, 13×13 and even 19×19, with 13×13 being the most popular. The great thing about Little Golem is that you can review every game ever played there. Most of the examples in this book come from Little Golem games.

For real-time play, the most popular sites are currently igGameCenter and PlayOK. hexy.games is a new website with real-time play of Hex and the related game Havannah.