Earthrise is a sci-fi MMO currently in development at Masthead Studios in Bulgaria, one which aims to merge sandbox gameplay with a post-apocalyptic setting. By all indications, Earthrise will be a game where players can band together to work towards world control, while of course struggling against opposing forces with similar goals.
This territorial control between guilds will be a key aspect of Earthrise and the latest 'Question of the Week' on the game's official forums addresses the game mechanics connected with such pursuits. Earthrise community manager Moll has posted "Siege Territory gameplay + defensive structures" which explains how guild bases will be integral in capturing and holding territory, as well as some of the ways these structures will allow guilds to tap the resources of a given territory. In addition, specific structures will allow for mass production, serve as power plants, and provide teleporters for moving troops between territories. There's plenty more info on the advantages of territorial control to be found in the latest round of Q&A's with the developers at Masthead Studios.