If you have multiple star spanning empires, they will likely develop a code of conduct, regarding what is neccessary to have a claim on some territory or resource and where someone else not honouring it, is a legitimate cause of war. Optionally there is some sort of UN, that can give at least some moral support for or against claims.
Who puts a colony there first gets the whole planet is the default assumption for most sf settings. But that allows an empire, that is militarily strong enough to threaten heavy retailiation, that makes lots and lots of colonies, each with 10 colonists. If something like that has happened in the past, propably starting a race, who can get their 10 colonists first at more planets, the wisdom of that approach might be questioned and the dominating powers might decide on a different code. Like that you have to keep a certain distance to existing settlements.
And if there are already lots of 10 inhabitant colonies, now that they are opened for further colonisation, in some of them other empires will place their own settlements as well.
An other scenario would be to have "wormhole" based FTL travel, propably with directional wormholes, and with a map, that makes multiple disjoint empires very difficult, since there are a few node worlds, that are essential to not be boxed in. If multiple factions contest the same node world, arrangements like everyone or everyone in a certain alliance gets a base on the node world will become feasable. Attempting to control a node world will likely be considered an affront in itself. And if some of theese states go to war, propably for a different reason, they will also fight on the node world, but will have to make sure, not to frighten all the other states, that also have outposts there.
One mans groundfloor is an other mans earthmissle @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Johannes Trimmel @@@@@@@@@@@@@@@@ _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
