At certain advanced technology levels, empires will acquire the capability to build large-scale deep space structures that will enhance the industrial and military strength of the empire. The following types of structures are known:
An outpost is a small, self-sufficient scanning station with a very small population, usually placed at the periphery of an empire. Outposts do not produce anything, but they are able to scan five sectors around them, keeping track of all objects that have been previously scouted by an imperial probe. Like other starbases, outposts can scan enemy fleets up to five sectors away (see Fleets).
Although they often possess GDMs and ion cannons for defense, outposts do not build defense satellites.
Self-Replicating Mines (SRMs) are the simplest structure to build. Once a few thousand seed mines are build, they will start building replicas of themselves out of metals and chemicals provide by ships. In a couple of years, millions of semi-intelligent mines will cover an entire sector, a volume of one thousand cubic light-years. Once placed, these mines will ignore passing warp ships, but if any enemy jumpships attempt to jump through the sector, the mines will immediately activate and detonate in a large super-gravity explosion, rupturing the jump-envelope and destroying any intruding ships in range. Of course, friendly jumpships will not activate them.
A command base is a mobile starbase equipped with the most sophisticated defensive weaponry. They often have a full complement of defense satellites, GDMs, and icon cannons, plus LAMs for long-range preemptive strikes. Although not as powerful or impressive as fortresses, they serve adequately as carriers protecting otherwise vulnerable fleets from attack as they penetrate into enemy territory.
Command bases have the scanning ability of outposts, allowing them to scan enemy fleets within five sectors.
These structures are actually giant shipyards built in empty sectors adjacent to mining or raw material worlds. Elaborate supply routes are set up so that the base can be specialized yet still be automatically supplied by its symbiotic world. Because of this combination of specialization and self-sufficiency, these structures are very efficient and cost-effective once the initial cost of construction is absorbed.
Once an industrial complex is build, it will consume the materials from any adjacent raw material, agricultural, or mining worlds and use them to build ships. Most complexes require a dedicated metal mine, a chemical plant, and a trillum mine. Industrial complexes may be designated to be base planets, jumpship bases, starship bases, or transport bases.
Once an empire acquires the technology to manipulate and harness super-gravity fields, the resulting revolution parallels those following the invention of the steam engine or the discovery of jumpspace. Warp links are giant super-gravity generators that literally bend and break space-time. A fleet passing through a warp link can travel to any other friendly warp link (or stargate) in a single year, regardless of the real-space distance between them.
Note: Mobile starbases such as command bases and fortresses are too large to pass through warp links or gates.
The same super-gravity technology that powers warp links and gates enables disrupters to distort and deform jumpspace. Any enemy jumpships within three sectors of a disrupter will be immediately forced to travel at a rate of a single sector per year. Friendly jumpships are, of course, not affected.
The height of attack technology, fortresses are large mobile battle stations that posses all the defensive capabilities of command bases. Their main weapon, however, is an internal limited gate that enables fleets orbiting the fortress to jump to any enemy target up to five sectors away.
As an attack carrier they can penetrate deep into an enemy's empire and then deploy battle fleets to one or more targets. Because even warp fleets can take advantage of the limited gate, an attack by a fortress has all the speed of a jumpfleet combined with the firepower of starships and penetrators.
The stargate (or simply "gate") improves the technology of the warp link so that a receiving station is no longer needed. A fleet entering a gate may travel to any point in the galaxy in a single year. Although at first thought this seems a simple and obvious improvement, the military and strategic ramifications are incredible.
Gates, when used by an experience emperor are so powerful that any empire possessing one may effectively prevent any other empire from completing their own. With their unrestricted destinations, gates may teleport battle fleets to unfinished construction sites, powerful base planets, or the very capital of the enemy empire. So destabilizing are they that most empires will gladly join forces against one that seems near to finishing a gate.