And really, saying you can't see stars not connected to starlanes a little bit hard to swallow ...
It's not that you can't see them, it's that they don't matter. From the perspective of some guy on a FreeOrion planet, there are billions and billions of stars in the sky: but only stars with lanes can be reached in a reasonable amount of time.
That sounds a bit more reasonable, though I'd still like there to be a whole slew of stars visible that you can't reach... yet. With time / effect, access would open up, and the places where you chose to expend more effort searching would be those where you think there might be a reason to do so, due to the proximity of lots of currently inaccessible stars.
I'd make it based 100% on discovery (though some techs would certainly improve the number of discovery points earned per turn.) The "lesser" starlanes would just have an insane discovery requirement.
stuff *might* have an effect on other stuff even if you can't see it.
I'm rather keen on technology having some effect on what you can see. Think of radio waves in human history... or the discovery of bacteria and viruses. It wouldn't have mattered how long someone looked around for either, without the appropriate technology to see them. (I refer to these in a fun-interesting gameplay mechanic sense, not a realism sense)
Various specials and starlanes could require a certain tech and
a certain familiarity level to be seen or explained or used. (and maybe different levels for each of those)
I'd also really like to have the ability (and necessity) of "widening" lesser starlane openings. All hard-to-see starlanes don't need to be small when found, but the ability to invest an effort to forge a path around the enemy's fortifications and surprise them on their back door is quite appealing to me.
For example, a planet might have hostile virus that reduces health. It'll reduce health on the planet, but you won't know it until a certain number discovery points are reached. Once it's discovered, a special build project is unlock: "Eradicate Virus."
Ah, but we'd probably need to have some notification that there is an effect happening, but just not tell the player what it is, or how to fix it. Ex: on the mouseover explanation for the bonuses/penalties to your health meter, you'd have +40 adequate world, +7 excess food supply, and -15 unkown... until you figure out what unknown is. Otherwise, the player would have to scan all his/her planets to look for irregularities and do mental math and such to figure out where there are negative effects happening without explanation.
We'd be able to give the player a general rating for each system, so he'd know which systems need more exploration, and which are totally, utterly explored.
I'm not sure a system should ever be known by the player
to be "totally, utterly explored" ... there's could always be new interesting stuff that you couldn't detect previously... due to tech advances and such, and just more time looking.
I imagine "stealing" another empire's Familairity maps would be a huge boon--through spy actions, salvage, or diplomacy. With the Familiarity scores, it would be easy codewise to exchange maps, since we wouldn't need to keep track of which objects each empire has discovered.
What if you're in a system, and observe someone going into a starlane you don't have enough familiarity to know about... do you detect it then? can you use it then? i assume you don't get familiarity enough to detect everything else in the system just from seeing the starlane in action.
Starlanes might require 10-30 Familiarity (rolled randomly for each lane). Wormholes 70-100. A lane to a black hole system would add +20 to it's Hide score. Specials would range from 0 to 100. Each planet/system/region special would have an "average Hide score" of which a random bell curved roll would modify.
I'd have a wider range of minimum familiarities for all things. Wormholes should pop up occasionally over the course of the game... not be only visible at the end when everything is explored.
For starlanes, after generating them, I'd have every system impose a the minimum familiarity on all the starlanes connected to it. Thus some systems would remain inaccessible until late in the game, whereas others would be fairly easily accessible. This would need to be done smartly, so that all homeworlds are interconnected with easy-to see starlanes at the start, but there are lots of hidden paths to other systems and ways around apparent bottlenecks that become more visible later.