Help for the Game of Osbo

Welcome to the network Osbo server. The challenge command is described here. Other commands are the same as for all pbmserv games.

osbo challenge [-size=n] userid1userid2 [userid3 [userid4]]

starts a new game for two to four players.

The -size=n option specifies the NxN grid size for each player (default 5x5).

Introduction

Osbo is a boardless dice game in which two or more players strive to complete the longest celtic knot.

Rules

Dice: Players share a common pool of six-sided dice showing knot segments on each face. Note that two of the faces are identical:

Each player has a separate playing area in which they grow their design. The game starts with a single die in each playing area showing the face with the most crossings:

Play: Players take turns rolling a number of dice (equal to the number of players) and playing each die face shown to extend their and their opponents' paths. Edge crossings must match edge crossings on neighbouring dice, and as many dice as possible must be played to as many players as possible each turn.

A typical move will therefore involve the current player adding one die (the best one!) to their own design and one die to each of their opponent's designs. Any dice left over due to players with closed designs may instead be played wherever the mover chooses.

Each player's design must fit within a 5x5 grid; moves that would allow a design to extend beyond this limit are not allowed. The following example shows an illegal move 'x' that would allow the design to extend beyond a 5x5 grid and a legal move 'y' that keeps it within the 5x5 limit.

Aim: The game ends when no players have any more moves (i.e. when all designs have been closed) and is won by the owner of the longest closed path. A path's length is measured by the number of crossings it contains, with self-crossings counting twice.

For example, the following mini-game between Fred and Ted has ended as both players' designs have been completed (closed). Ted has won this game with a path of length 6 even though Fred has more total crossings; Ted was able to maintain a single closed path while Fred's design contains two shorter closed paths of length 4.

Notes

Players should strive to maintain a single path with as many extension points as possible in their own design while attempting to split enemy designs into multiple shorter paths with limited extension points.

Dice faces with more crossings are more useful in the early game, while dice faces with fewer crossing are more useful in the end game.

An NxN game with P players will require NxNxP dice. For instance, a standard two-player 5x5 game will require 50 dice.

Osbo is perverse in that players with completed designs - and hence no moves for themselves - still actively participate in the game and can even decide the eventual winner. This kingmaker effect is generally taboo in multiplayer game design but has been deliberately incorporated so that players must think carefully about who they attack; if A consistently hurts D, then D will take revenge when the opportunity arises (McCarthy's Revenge Rule). In fact, players with completed designs have extra blocking power as they no longer need to save the best die for themselves and will have at least one free die with which to wreak havoc. Players must therefore try to eliminate opponents without annoying them in the process. Tricky!

Another reason that players with closed designs remain active in the game is that they may not only decide the winner, but may go on to win the game themselves. Even players who have resigned and left the game may still win if they have achieved a closed path of sufficient length before retiring.

The fact that players may play to all opponents each turn makes move order less important than in other games. This provides a balancing mechanism which means that the last player does not necessarily get the worst deal.

The moves made each turn are highlighted in the board display so that players can keep tabs of who is being nice to them and who isn't.

Syntax

This command places die face 'a' at position 3 and die face 'f' at position 12 (positions 3 and 12 will typically belong to different players).

Options

-play_closed:     Players who cannot extend their own design must still place dice (default on).-skip_closed:     Players who cannot extend their own design are skipped (default off).
-play_extra:       Extra dice may be played to any players (default on).-skip_extra:       Extra dice may not be used - only one die per player (default off).
-can_expose:       Players can run open path ends into the NxN border to kill them (default off).
-cant_expose:     Players cannot run open path edges into the NxN border (default on).
-auto_tips:         Open path edges on the NxN border are automaitcally closed by a tip (default off).
-no_auto_tips:   No auto tips (default on).

History

Osbo was inspired by celtic knotwork (or "not work" as my boss Quentin used to call it) and the wish to design a game that produced works of art as it was played. "Osbo" is a Proto-Celtic word meaning "knot".

The NxN grid constraint was inspired by the game of Tashkent Dominoes. This constraint, used to good effect in many other games such as Trax, ensures that players cannot indefinitely diverge opponents' paths away to keep them open and that games converge to a solution.

The -auto_tips option is reminiscent of the automatic snake head placement in Schlangennest, as suggested by Stephen Tavener.