Welcome to the network Margo server. The challenge command is described here.
Other commands are
the same as for all pbmserv games.
margo challenge [-size=number] [-height=number] [-can_pass] [-all_freedoms] userid1
userid2 [.. userid4]
starts a new game for between two and four players.
The -size parameter sets the size of the board (default is 8).
The -height parameter sets the maximu height for pieces (default is infinity).
The -can_pass parameter specifies that players may pass.
The -all_freedoms parameter specifies that freedoms may exist at any height and not just the board level.
Margo is similar to Go played with marbles, except that groups may stack upwards over enemy pieces to join up with other groups. A special capture means that captured pieces which support higher-level enemy pieces are not removed.
Play: Players take turns placing a piece (marble) of their colour at any valid empty point. A point is valid if it is: 1) a board point, or 2) supported flatly by four existing pieces. Players may not pass.
Connection: Two pieces of the same colour are connected if they are squarely adjacent to each other, or one rests directly upon the other. A group is a visibly connected set of pieces which may visit multiple levels.
Freedom: A piece has freedom if it is adjacent to at least one valid empty point on the board level. A group has freedom if at least one of its member pieces has freedom.
Surround capture: After playing a piece, all enemy groups without freedom are captured and removed from the board, except for pieces that support one or more higher-level pieces of a different colour either directly or indirectly. Such pieces are not removed and remain alive in the game.
No suicide rule: It is not permitted to place a piece without freedom, unless that move captures neighbours to create its own freedom.
Ko rule: It is not permitted to repeat a previous board position (this has not been implemented so is up to the players' discretion).
Over/under rule: A connection passing over an enemy connection cuts it. Buried pieces (those with a piece directly above them) do not count in any connections; groups must be visibly connected.
Winning: The game ends when the current player has no legal move. The player with the most pieces in play wins.
An X piece at 'a' captures the O group, which has no remaining freedoms. | . . . . | . . . .
| ___ | ___ ___
| / \ | / \ / \
| a ( x ) . . |( X | x ) . .
| ___ \___/ ___ | \___/ \___/ ___
| / \ / \ / \ | / \
|( o | o | x ) . | . . ( x ) .
| \___/ \___/ \___/ | \___/
| / \ / \ / \ | / \
|( o | o | x ) . | . . ( x ) .
| \___/ \___/ \___/ | \___/
| / \ / \ / \ | / \
|( o | o | x ) . | . . ( x ) .
| \___/ \___/ \___/ | \___/
+----------------------- +----------------------- An X piece at 'b' does not capture the O group, as it still has two freedoms after the move (marked '*'). | . . . . | . . * .
| ___ ___ | ___ ___ ___
| / \_/ \ | / \ / \_/ \
| b ( x/ \o ) . |( X | x/ \o ) *
| ___ \_( o )_/ | \___/ \_( o )_/
| / \ / \___/ \ | / \ / \___/ \
|( o | o | x ) . |( o | o | x ) .
| \___/ \___/ \___/ | \___/ \___/ \___/
| / \ / \ / \ | / \ / \ / \
|( o | o | x ) . |( o | o | x ) .
| \___/ \___/ \___/ | \___/ \___/ \___/
| / \ / \ / \ | / \ / \ / \
|( o | o | x ) . |( o | o | x ) .
| \___/ \___/ \___/ | \___/ \___/ \___/
+------------------------ +----------------------- An X piece at 'c' captures the O group. Note that captured pieces which support the higher-level X piece are not removed. | . . . . | . . . .
| ___ | ___ ___
| / \ | / \ / \
| c | x | . . |( X | x ) . .
| ___ \___/ ___ | \___/ \___/ ___
| / \ / \_/ \ | / \_/ \
|( o | o/ \x ) . | . ( o/ \x ) .
| \___/ \_( x )_/ | \_( x )_/
| / \_/ \___/ \ | / \___/ \
|( o/ \o/ \x ) . | . ( o | x ) .
| \_( o | o )_/ | \___/ \___/
| / \___/ \___/ \ | / \
|( o | o | x ) . | . . ( x ) .
| \___/ \___/ \___/ | \___/
+----------------------- +----------------------- The O overpass cuts the following two X pieces (over/under rule). . . . . ___ ___
/ \_/ \
. ( o/ \o ) .
\_( o )_/
/ \___/ \
. ( x/ \x ) .
\_( o )_/
/ \___/ \
. ( o | o ) .
\___/ \___/
. . . .
Higher level plays are strong, as the lower-level pieces that support them remain fixed and cannot be removed from the board (unless the higher level pieces are themselves captured and removed). It is therefore generally good to stack on friendly pieces but not enemy pieces.
Multiple groups may be joined by higher-level pieces to create safe supergroups with multiple eyes. However, the fact that players may not voluntarily pass means that they may eventually be forced to fill in their own eyes and render groups unsafe.
Since pieces are counted rather than territory, scores are tied at the end of each round until a capture occurs. However, the fact that players may not pass, and hence at least one capture is more or less inevitable, ensures that most games will have a clear winner. Territory is therefore an important secondary consideration, as the player that commands the most territory in the end game is the most likely to survive an eye-filling race.
Adjacent friendly pieces on the outermost row or column of any level cannot be cut, as it's not possible to bury them or separate them with an overpass. Edge moves can therefore be quite strong (especially if they support higher-level pieces) despite the fact that the edge removes a potential freedom. Edge play becomes increasingly predominant as the levels build up and the ratio of edge points to interior points increases.
The special capture rule (that pieces supporting higher-level enemy pieces are not removed) is necessary to avoid the fiddly problem of retrieving buried pieces after capture, and also avoids the problem of higher-level enemy pieces settling down in random directions if support pieces are removed. It also adds some additional tactical interest to the game, since players will have to carefully weigh up the benefits of building upwards if that move would pin enemy pieces.
Removing buried pieces from connection calculations means that players do not have to remember the colour of hidden pieces, except when it comes to counting the score at the end of the game.
The board, when fully stacked, forms a pyramidal or cannonball stacking. The maximum number of pieces that may be played on a board of size n is given by the pyramidal number Pn = n (n + 1) (2n + 1) / 6.
Board size Max pieces
3x3 14
4x4 30
5x5 55
6x6 91
7x7 140
8x8 204
9x9 285
10x10 385
11x11 506
12x12 650
13x13 819
... ...
19x19 2,470
A game of Margo will therefore take several times as long as a game of Go on the same sized board. For example, a 10x10 Go board has room for 100 pieces whereas a 10x10 Margo board has room for 385 pieces (although these limits will never actually be reached).
Each ball in a cannonball stacking has up to twelve connected neighbours, however, only four can possibly count as freedoms for any piece. These are the four squarely adjacent board level neighbours (as in Go) not diagonally adjacent neighbours on the next level up/down. This is for two main reasons:
1) It makes groups easier to surround (otherwise captures would rarely occur); and
2) It means that some members of surrounded groups may remain uncovered (otherwise only singleton captures would remove pieces from the board).
Translating Margo to the hexagonal grid is complicated by phase problems; for any packed level there are two ways to pack the level above, both of which are valid but incompatible. The square grid is better suited to ball-stacking games of this type.
You can set the display size according to your own perverse taste. The large display size is recommended for smaller boards (7x7 and less), the medium display size is the default, and the small display size is recommended for larger boards (12x12 and over).
_____ _____
/ \ / \
| o o | x x |
| o o | x x | "margo set <username> <password> large"
\_____/ \_____/
___ ___
/ \ / \
( o | x ) "margo set <username> <password> medium"
\___/ \___/
.-. .-.
( o | x ) "margo set <username> <password> small"
`-' `-'
Players wanting a shorter game can either choose a smaller board size or use the -can_pass option to allow passing. The player that achieves the first advantage will generally carry this advantage through the game and win it if they are allowed to pass.
If players are not allowed to pass, however, the game enters a further (cold) phase in which they are forced to fill in their own eyes or make otherwise disadvantageous moves. The adds to the drama of the game, since the losing player may eventually force a win if they have managed their territory more cleverly than their opponent. Territory plays a much more important role if passing is not allowed.
Multiplayer Margo is played using the same rules as the two-player version, however a couple of clarifications are warranted.
An X or Y piece at 'd' captures to O group, which has no remaining liberties.
| . . . . | . . . .
| ___ | ___ ___
| / \ | / \ / \
| d ( x ) . . |( X/Y | x ) . .
| ___ \___/ ___ | \___/ \___/ ___
| / \ / \ / \ | / \
|( o | o | y ) . | . . ( y ) .
| \___/ \___/ \___/ | \___/
| / \ / \ / \ | / \
|( o | o | x ) . | . . ( x ) .
| \___/ \___/ \___/ | \___/
| / \ / \ / \ | / \
|( o | o | y ) . | . . ( y ) .
| \___/ \___/ \___/ | \___/
+----------------------- +----------------------- The X/Y overpass cuts the following two O pieces (over/under rule). . . . . ___ ___
/ \_/ \
. ( x/ \x ) .
\_( x )_/
/ \___/ \
. ( o/ \o ) .
\_( y )_/
/ \___/ \
. ( y | y ) .
\___/ \___/
. . . .
Some multiplayer Go variants relax the connection definition so that enemy groups may consist of stones of any colour except the current player's. Margo maintains the stricter definition (that any group may only consist of one colour) to encourage captures.
The move syntax is:
margo move board# userid password a7 (place a piece at A7)
margo move board# userid password swap (swap sides - second move only)
margo move board# userid password a7x (place a blocking piece at A7 - for testing only)
Margo rules copyright (c) Cameron Browne, February 2006.
The name "Margo" = Marbles + Go.
More details are available at the official Margo page.
Implementation and Help file by Cameron Browne, February 2006.