If it works (well enough) in WINE, or if there's a linux binary, I'll be buying it.
Not a strict requirement with me, but it'll certainly help, as I currently don't have much motivation to not move onto linux. Windows systems are bloated, buggy, allow little user intervention and are built ass-backwards. The only thing that has managed to keep me on windows for so long was gaming, and it's currently going down the gutter, so yeah.
on the side-topic of realistic physics; imho, e2:f had the best dogfighting in the whole series. There aren't car-style chases like in FFE, it's all orbital and slingshot and wait an hour til they come back in range, then FIRE!
I must call you out on that, my good sir.
Apart from annoying and undesirable manoeuvring "assist" that costed me many a moment of grief and frustration, but is almost unnoticeable in most circumstances, and apart from greatly improved AI in FFE (pirates in FE2 couldn't hit the broad side of Coriolis station from half a km away) combat mechanics in both games was identical, courtesy of the physics, ranges and ship parameters being identical.
The only difference was that FFE cut off the "velocity adjust mode" when the ship was attacked, while in FE2 you had to do so manually by switching into "engines off" mode. If you hadn't, the ship tried to match it's velocity vector to the one specified by the pilot, according to the frame of reference, no matter that both the ship and the enemy was hurtling through space at several thousand of km/s according to this FoR. This resulted in rather nonsensical and utterly uncontrollable "jousting". You can still joust in FE2 and FFE at the beginning of the combat (to get relatively close to the enemy, without getting melted by their suppressive fire), if you're inexperienced or if your ship is much more sluggish than the enemy vessel, but, other than that, both in FE2 and FFE the combat consisted of precise directed burns in attempts to get relatively close to the enemy while staying out of their line of fire. All in all, the combat was very anachronistic, but physically correct - in neither game did it emulate WWI dogfights in SPAAAACE!
I know most people are APPALLED by the thought of realistic space fighting, but i maintain, the problem isn't the physics of the endeavor aren't fun, it's the weapons don't match the environment, if the weapons were better designed (and shipboard computer assisted) for the relativistic, constantly shifting orbits of the combatants, it could be more fun.
I, personally, am enthralled by it.
Also, regarding "relativistic" - last time I checked there were no plans to make E4 Einsteinian, but if it turned out to be the first spacesim of this type, I will surely make Braben a lot of bad publicity by entering the berserk rage whenever someone says this game sucks and inflicting grievous bodily harm on them (possibly even
grievous harm with a body)

.
ships in E4 should have the "Match Velocity" feature in targeting computers (of a certain quality) like in Terminus, which would rapidly adjust-to-match your reference velocity that of your target's, so you could accelerate/decelerate at a rate IN REFERENCE to your target. That solves most peoples problems with the relativity of combat.
That'd be good, as long as it's optional. While displaying your velocity relative to the target, and possibly even HUD visualizations of surrounding objects' relative velocity vectors (like in otherwise arcade-y Darklight Conflict) at all times would hurt no one, I'd rather still use precise fully manual burns most of the time given the choice.
As for the slider, I will elucidate below.
It depends on the games setting for me. I think it'd be great to feel like your in a real universe where it's dark and how you'd imagine space to be, but I also think there should be those out-of-this-world visuals happening in the landscape (like the above image) that you see when flying. To me, it should make me think "wow, maybe this is really out there somewhere" as that adds to the enjoyment of seeing something I can't see in real-life, or haven't already seen in other media.
"wow, maybe this is really out there somewhere" feeling is best facilitated by the sight that can be out there somewhere.
Colourful nebulae / landscapes can always be supplemented by events as well, like capital ship graveyards or the remnants of a planet so it's easy to make space look interesting, but not unrealistic.
Nebulae should definitely be a rare sight, and only applicable, when you're close enough to them. The backdrops in general should ideally look like darkened and toned down backdrops from the first Homeworld. IMO, the best idea would be to generate backdrops during the hyperjump by mapping the densities and colours of surrounding stars, gas and dust clouds onto the celestial sphere. Bright/nearby stars would be rendered individually, while the rest only as nebulous haze.
Things like ship graveyards (possibly ancient alien ship graveyard bristling with promises of alien artifacts and tech in some Lagrangian point on the fringe of the explored space or beyond), remains of some superstructures, maybe even abandoned alien portal network that can be reactivated and used to venture far beyond the normal jump range, cities and stations, including giant aerostates in gas giants' atmospheres, crawling cities staying on the night hemisphere on planets orbiting too close to their suns, orbital elevators, rare gas giants where some sort of biosphere evolved in the atmosphere, rare
Smoke Ring style or
Rocheworld worlds etc. can all add flavour to the game without making it unrealistic. See Niven's work for further examples that realism doesn't equal boredom - this guy is the master of settings, also check some artistic, but astronomically correct renditions of extrasolar planets and their possible landscapes:
http://www.extrasolar.net/usage.asp
For extra nerdgasms,
do check the site itself,
especially
science and
planets sections.
Newtonian physics brings up an entirely new debate, such as can a Newtonian physics flight model (simulator style) co-exist with an arcade-like physics flight model (casual style)? ...Especially when considering multiplayer.
I think it's ass backwards approach. Instead of trying to introduce different kinds of physics, which would create all sorts of problems with the AI, balance and, in multiplayer, mess up the game for the people using different setting (if only because the other players' ships might behave in the way contradicting their expectations), the "Training wheels" approach should be used.
Rather than altering the physics, there should be an option that made the ship emulate arcade behaviour using it's thrusters, without ever exceeding it's physical capabilities. Sort of extension and extrapolation of the "manual" mode from FE2.
Obviously, the important feature of the training wheels is that they can be discarded at will.
The multiplayer would have to sport some alterations of the singleplayer mechanics - with no stardreamer, there should be an option to do some in-system jump. Of course, the mechanics in singleplayer should be unaffected by that.
Shoddy, sloppy worksmanship with little interesting content. The Spore, really, says it all for me...
So does Oblivion.
