Get domination in space.
STRUCTURES: CITADEL & COMPLEX & REFINERY
Citadels are upwell structures meant to be used as operation bases. They receive bonuses to combat rig effectiveness, market service fuel usage and cloning bay fuel usage. Citadels also have the shortest vulnurability durations and strongest combat options making them easier to defend.
The three citadels are Astrahus (medium), Fortizar (large) and Keepstar (extra large). They have exactly same structure bonuses so the difference is only how much things they can have fitted, how long vulnerabilities they have and how much of a status symbol they are.
Engineering complexes are the structures of choice for research and manufacturing. Research and manufacturing services installed in engineering complexes consume less fuel. In addition the engineering complexes have innate bonuses to manufacturing material usage, manufacturing and science job duartions and manufacturing and science job installation fees.
The three engineering complexes are Raitaru (medium), Azbel (large) and Sotiyo (extra-large). All three limit their docking to battleships and below so once a built capital ship comes out it can not go back in.
Refineries are structures of choice for refining materials, reactions and moon mining. These are the only structures that can do reactions or moon mining and also receive innate bonuses to refining yelds and both reprocessing and refining service module fuel consumtion.
The two refineries are Athanor (medium) and Tatara (large). The athanor docking is limited to only subcapitals while Tatara also allows rorquals to dock.