Just repeat to yourself, "It's a game."

You are speaking like you know how a theoretical future civilization would work from our fairly primitive perspective.  Its like a bunch of coyboys in 1850 saying that something like nuclear reactors, cell phones that let you speak to anyone from practically anywhere (which was considered really exotic just a few decades ago in the 60s... just watch the original star Trek series) , submarines that can go to the bottom of the ocean, etc. are just impossible.

Also, why would it be hard to find a ship in a cubic light year of space?  You just go to where your sensors say the exotic metal and compounds are.  Its not like that cubic light year of space is filled with rare materials that require the actions of an advanced civilization.  That cubic light year of space is primarily filled with nothing.  Again, us saying it is impossible is like a bunch of coyboys from 1850 saying anything today is impossible.  If you could travel back in time and tell the coyboys what technologies we have now, they would look at you like you were completely insane.

Exerting influence via a culture starbase was quite believable in GCII with the modules, (concerts, night clubs etc., etc.). I don't recall all of them but it was an impressive list.

When you build a star base with all those attractions nearby a rival planet, it is bound to have a strong effect.

The suspension of disbelief is not required to buy into the effectiveness of the star base, but it is still needed to overlook the high degree of likelihood that an alien civilization would not understand or have any interest in our culture.

The Ansible

 The physics of the universe are rather well known.  And so are the distances.

Light only moves so fast.  If you (somehow) move faster, then no one can see you coming.  Like the bullet that travels faster than sound, it arrives before it is announced.

Distances in space are vast beyond comprehension.  Looking for a fleet in interstellar space would be near impossible, not only for the problem of detecting emissions the only move at the speed of light, but the vastness means that meeting for combat would be so improbable that the chances of it happening wouldn't occur before the end of the universe.

Using the 1700s as an analogy, fleets at sea found it hard to locate each other in the proportionally smaller oceans.  Even with radar and satellites it's still tough.

It would be like trying to find a specific grain of sand located between the earth and the sun. 

It is possible to detect reasonably sized and reflective/emmissive objects in the solar system but all those sightings are historical by hours to weeks depending on how far out the object is. 

Even if you had some sort of FTL sensor, distances degrade resolution to a degree that again it becomes useless for general searching quickly.

Battles in deep space simply aren't going to happen.  And strategically you wouldn't want to do it anyway as you'd want to keep your war assets close to whatever is valuable.

-

There's no possible mechanism for 'space stations' located in a particular solar system to influence anything out side that solar system.  In fact it would be difficult to have influence beyond the planet it's orbiting.  It's inane for a space story or game. 

These two game mechanics are simply ridiculous.

--

The wildest theories on how FTL would be accomplished all point to it being extraordinarily expensive in energy use and requiring exotic materials that don't exist outside of theory. 

So if in the game or story using FTL is common as getting in your car, the game or story going to feel silly and improbably.  Like the early speculations that we would all travel by personal jetpack or have our own personal balloons to carry us about.

Unless of course this is a game based upon 'The Jetsons' and you can flit to another planet in the family car in a few minutes.  Or you're Fred Flintstone and it's practical and desirable to push a cart of made of logs and stone wheels to and from 'work'.

Of course there is no way that our understanding of the physical universe might change in the future or tech might advance in directions we cannot now comprehend. . .

Immersion for me is more about maintaining the atmosphere and story as I play through a game.  The science doesn't have to be realistic, as long as it's consistent.

The problem isn't space opera, it's doing things that make no sense.

Some other neat science issues:

http://io9.com/12-ways-humanity-could-destroy-the-entire-solar-system-1696825692