Create a new technology branch, so it is possible to crete diseases and spread them throuhg espionage in enemy empires planets, and slow o decrease their birth rate, even, eliminate population from planets and leave theses planets as conolizables.
Create a new kind of anomaly, the worm-hole. When you send ships through a worm-hole, they appear in the other extreme of the worm-hole, that could be in the opposite side of the galaxy. Maybe, it could be interesting, treat it as a new technology branch (Galactic-Achivement), that allows you the creation of worm-holes (with a maximun number), so you can use it for commercial or logistics purpouses. Even, you could rent the worm-hole to third parties...
Create within the shipyard, additional modules, which make possible creating ships that can deploy mine fields, so that, only "allies and commercial ships" can travel (of course your own ships). This way, you can create defensive walls for your empire.
Create a new Research branch, so it is possible creating cloaked fleets, that can be strategically station until you perform an attack.
Create a new Research Branch, so you can create fleets that are "un-identified", you control it, but enemies are not sure who is in charged of them. These way, you can iniciate attacks against other empires (punishment missions), without beginning a war.
Sorry in advance if the idea has been propoused previously... I think it could be interesting a PSI Corps research branch. PSI Corps (like PSI Corps in Babilon 5) leverage the power of mind, so, you can create fleets based on this ability. This kind of fleets, can influence enemy fleets (fear), or make enemy fleets defeat their empire and join yours. Of course, this could be "your enemy strategy", so, you get to counterstrike this tactic, joining PSI-Corps craf
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