## Help For CoNeutron

### Introduction

Welcome to the network CoNeutron server. The rules of CoNeutron are below. The commands are the same for all pbmserv games.

neutron challenge userid1 userid2 [ -size=number ]
Start a new game between userid1 and userid2.
The -size option can be used to set the board size to any odd number greater than or equal to 5.

CoNeutron is based on the game of Neutron. When playing Neutron it became clear the game lacks balance and the first player to move (even when his first move is restricted to only moving a pawn) has an enormous advantage. Discussing the subject, this solution to get a more balanced game came up and because the code for Neutron hardly had to be changed, it was implemented soon after.

### THE RULES

CoNeutron is played by 2 players on a 5x5 square board. The players sit on opposite sides of the board. One plays white, the other plays black. The row closest to the player's side is called his back row.

```                 A   B   C   D   E
+---+---+---+---+---+
1 | x | x | x | x | x | 1 <- Black's back row
+---+---+---+---+---+
2 |   |   |   |   |   | 2
+---+---+---+---+---+
3 |   |   | * |   |   | 3
+---+---+---+---+---+
4 |   |   |   |   |   | 4
+---+---+---+---+---+
5 | o | o | o | o | o | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E
x = Black pawn  o = White pawn  * = Neutron

Figure 1.  Beginning of CoNeutron.
```

The game starts with the set-up as shown in figure 1. Figure 1 also shows the characters A, B, C, D and E and the numbers 1, 2, 3, 4 and 5. These are used to give coordinates to determine the position of the pieces on the board. For example the neutron starts at position C3.

### WINNING

A game of CoNeutron can be won in 2 ways:

1. a player moves the neutron to his OPPONENT'S back row or forces his opponent to move it there.
2. the opponent can not make a complete turn (usually this means the neutron will be trapped and impossible to move).

### MOVING

The players take turns on making moves. White moves first. All pieces move in exactly the same way. They move in a straight line in one of the eight possible directions, and they must go as far as possible. Specifically, they must travel in a straight line until they bump into another piece, or the edge of the board. A complete move consists of moving first the neutron, then one of your own pieces.

On the initial setup, this means the neutron can go to either A3 (straight horizontal line to the left), B2 (straight diagonal line up and left), C2, D2, E3, B4, C4 or D4. It can NOT stop at B3 because it has to be moved until it reaches the side of the board or runs into another piece! The pawns are moved in the exact same way: in a straight line, and as far as they can go.

### NOTATION

The moves are notated as

[coordinates of neutron destination],[coordinates of pawn]-[coordinates of pawn's destination]

So if on White's first turn he/she decides to move the neutron to A3 and the pawn on B5 to B2, it is notated as 'A3,B5-B2'.

If the neutron can be moved (or is forced to be moved) in a way that ends the game (meaning: finishing on a back row), then only the neutron move has to be notated: 'A5'.

### REFERENCE TO NEUTRON

CoNeutron is based on Neutron. It only differs on 2 points:

1. The winning condition is moving the neutron to your OPPONENT's back row, where in Neutron you win by moving it to your OWN back row.
2. There is no exception on the first move, so White moves both the neutron and a pawn.

You can get the rules of Neutron by sending 'help neutron.rules' to Richard's PBeM Server (pbmserv@gamerz.net).

### EXAMPLES

Because my description of the rules may have left you puzzling, here are some examples:

1. Making a move.

Here's a situation as it might occur in a game of CoNeutron:

```                 A   B   C   D   E
+---+---+---+---+---+
1 |   |   | x |   | x | 1 <- Black's back row
+---+---+---+---+---+
2 | x | x | x |   |   | 2
+---+---+---+---+---+
3 |   |   | * | o |   | 3
+---+---+---+---+---+
4 |   |   | o |   |   | 4
+---+---+---+---+---+
5 | o |   | o | o |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

It's White's turn to move. First he must move the neutron. It can be moved to A3 (runs into a side-wall), B4 or D2 (runs into a pawn) or to E5... most likely White won't move to E5, because that will lose him the game (see example 2). The neutron can NOT be moved to B3 (it has to go as far as it can), C2 (capturing of pieces is not allowed), A1 (jumping is not allowed) or E4 (can not be reached in a straight line). Let's say White moves the neutron to A3:

```                 A   B   C   D   E
+---+---+---+---+---+
1 |   |   | x |   | x | 1 <- Black's back row
+---+---+---+---+---+
2 | x | x | x |   |   | 2
+---+---+---+---+---+
3 | * |   |   | o |   | 3
+---+---+---+---+---+
4 |   |   | o |   |   | 4
+---+---+---+---+---+
5 | o |   | o | o |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

Now White has to make a choice which pawn he will move. He can only move his own pawns, the white ones, that are indicated with 'o'. He decides to move the one at D3. He can move it to B3 (runs into the neutron), D1 or E3 (runs into a side-wall) or D4 (runs into another pawn). He can NOT move it to A3, C2 or C4 (capturing is not allowed), B1 (jumping is not allowed), E5 (can not be reached in a straight line) or C3 (it has to go all the way).

If White chooses to move his pawn to E2, his complete turn can be notated by: 'A3,D3-E2'.

2. Winning by moving to your opponent's back row.
```                 A   B   C   D   E
+---+---+---+---+---+
1 |   | x | x |   |   | 1 <- Black's back row
+---+---+---+---+---+
2 |   | x |   |   | o | 2
+---+---+---+---+---+
3 | x |   | x | o |   | 3
+---+---+---+---+---+
4 | * |   | o |   |   | 4
+---+---+---+---+---+
5 | o | o |   |   |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

It's White's turn to move. He can win this game by moving the neutron to D1 (a straight diagonal line).

3. Winning by forcing your opponent to move the neutron to his own back row.
```                 A   B   C   D   E
+---+---+---+---+---+
1 |   | x | x |   |   | 1 <- Black's back row
+---+---+---+---+---+
2 |   | x |   |   | o | 2
+---+---+---+---+---+
3 | x |   | x | o |   | 3
+---+---+---+---+---+
4 |   | * | o |   |   | 4
+---+---+---+---+---+
5 | o | o |   |   |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

Again, it's White's turn. The move A4,C4-B4 will give this board:

```                 A   B   C   D   E
+---+---+---+---+---+
1 |   | x | x |   |   | 1 <- Black's back row
+---+---+---+---+---+
2 |   | x |   |   | o | 2
+---+---+---+---+---+
3 | x |   | x | o |   | 3
+---+---+---+---+---+
4 | * | o |   |   |   | 4
+---+---+---+---+---+
5 | o | o |   |   |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

Now it's Black's turn. First he has to move the neutron. But that can only go one direction: up and to the right. Also he has to move the neutron as far as it can go, so Black has to move the neutron all the way to D1 and he loses the game.

4. Winning by closing in the neutron.
```                 A   B   C   D   E
+---+---+---+---+---+
1 |   | x | x |   |   | 1 <- Black's back row
+---+---+---+---+---+
2 |   |   |   |   | o | 2
+---+---+---+---+---+
3 | x | x | x | o |   | 3
+---+---+---+---+---+
4 |   | * | o |   |   | 4
+---+---+---+---+---+
5 | o | o |   |   |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

Ah, Black is learning! He has closed the gap to D1! But if White now moves A4,C4-B4 this will result in:

```                 A   B   C   D   E
+---+---+---+---+---+
1 |   | x | x |   |   | 1 <- Black's back row
+---+---+---+---+---+
2 |   |   |   |   | o | 2
+---+---+---+---+---+
3 | x | x | x | o |   | 3
+---+---+---+---+---+
4 | * | o |   |   |   | 4
+---+---+---+---+---+
5 | o | o |   |   |   | 5 <- White's back row
+---+---+---+---+---+
A   B   C   D   E```

Now it's Black's turn. He has to move the neutron, but can't! Therefore he loses the game... again.

NOTE: these are all examples... Black doesn't lose all the time :)

### ACKNOWLEDGEMENTS

C.D.Wright told me about a CoNeutron Tournament run at Cambridge University. It was run by Mark Owen and Julian Richardson. They had modified the rules of Neutron to make it more balanced and therefore they are the inventors of CoNeutron.

Søren Pingel Dalsgaard coded and implemented the game for Richard's PBeM-server (pbmserv@gamerz.net).

Richard Rognlie made it all possible by setting up Richard's PBeM-server for us games addicts.

The first game of CoNeutron on Richard's PBeM-server was played between Ronald Lokers and Søren Pingel Dalsgaard in November, 1997. Søren won :(

Ronald Lokers, November 21, 1997