Astrophysics: A new, very powerful, highly coslty tier in tech tree.
Astrophysics basically means stellar manipulation - that you can influence and even manipulate stellar objects like suns, planets, asteroids, even black holes and everything else. Stellar manipulation is a way of shaping cosmos (galaxy map) and circumstances for you or your opponents as you wish. There are lots and lots of strategic options and powerful inventions one can imagine as soon as thinking of stellar manipulation.
The options imaginable can be so powerful that they shape additional alternative how to win in the long term other than by military means. Right now we have influence/cultural control, espionage is developing and there are other ways such as alliances. But there can be even one way more how to win other way than military, which is stellar manipulation. With massive investments and insane effort at the beginning (and faster, easyer goals/achievements as player develops), one could slowly but surely have the power over the galaxy that cannot be challenged no matter the opponent’s fleet size.
A human could shape the galaxy as he desires. Black holes alone could offer sense of power previously undreamed of. There could be tech projects so large, tasks so difficult that it makes sense to try joined efforts (alliances) to make something happen. I do not mean teleportation wormholes or planet busting weapons – these are relatively easy. I mean black hole creation/abuse or artificial/synthetic planet creation.
Make the nature of the Universe the most difficult „enemy”, the most challenging obstacle to overcome, not the other players in the map. For example: There is a room in every sun system for so much planets and so large planets as much the sun’s gravity can take. So now (sun’s) „size matters”. It is scientific fact that our star „Sol” can have approximately 10 Saturn sized (class XX) planets, for example. These can be artificially created and those already being there (dead planets) could be „terraformed”. All planets in system could now be synthetic and all synthetic planets could have ALL tiles buildable. This is just an example. There can be more sophisticated projects, like other dimensions. It is scientific fact that understanding quantum physics requires understanding physics beyond the conventional reality borders. This principle can be developed further and whole new dimension(s) can be invented. The whole galaxy map can be seen from different angle, from that of other dimension, by simply pressing Ctrl + d, for example, and the map is drawn again anew, much like the map is drawn when you zoom out. The player could see and interfere in other players plans by the means of other, more sophisticated physics, more sophisticated means. Some time ago people couldnt even imagine that such thing as cyber warfare could even exist and be extremly serious form of war. The same thing with exotic physics.
But, of course, there could be easyer goals to achieve than travelling through dimensions, through convetional physics. For example: Stellar storms dischargeable (having bomb effect, damaging travelling ships when/if player desires). Invisible shields that opponent (that is unaware of the tech) cannot pass and make all the travel in vein. Supergravity that, once applied to planets/stars, creates flypaper effect – sticking the nearby fleets to the planet and thus freezing them there till eternity (unless countermeasures by the player developed). Projects like these, and so on, and so on.
Think astronomical. Invent strategic buildings that make astrophysical projects happen. Make places unique.
In the big picture, Astrophysics gives unseen meaning to EXpansion phase, allowing EXpansion till the very end of late game.