Welcome to SSC, OP - see my sig! <chortles>

X3 terran conflict and it's expansion pack x3 albion prelude might be the best. There's other sims some people like/don't like x:rebirth, star wolves 3 , starpoint gemini 2, galaxy on fire 2,  evochron mercenary and i-war 2. Elite dangerous might be an open world space sim? Check out the games listed on the main pages side bar theres a pretty good list.

Welcome to SSC, OP - see my sig! <chortles>

Indeed! Oolite is amazing in its content. Be careful though as if you try it you will find an ever growing need to add OZX packs to it. I have......um.....er......100s of the things installed.

Also have a look at Pioneer (the is a link in my signature), Genesia & Pioneer Scout Plus. All these are free.

Alternatively you could try and find copies of Freelancer, Spaceforce Rogue Universe & Tachyon The Fringe. These are getting on a bit these days but still solid stuff and fully offline play.

Second Starpoint Gemini 2 and Drifter and Dangerous are both worth a look although both started as mobile game then made the leap to PC.

If you haven't played it yet, I think I-War2 is an absolute must, even though it's now quite old.  Probably the best one ever made, in my opinion (although there are some infuriating and totally inappropriate difficulty spikes).  Also, the very old but slightly more modern X-Wing vs. TIE Fighter and X-Wing Alliance are now on GOG.

Good suggestions. Starpoint Gemini 2 I now have on order.

I-War2 - I'm in 2 minds about. It does sound pretty brilliant from some reviews but the Newtonian movement doesn't appeal and as you state, there are numerous reports of horrendous difficulty imbalance coupled with a major bugthat doesn'tlet you get past one of the missions etc. Might still have to try it tho.

I-war 2 is $1.50 usd on gamesgate currently.

http://www.gamersgate.com/DD-IWAR/independence-war-2-edge-of-chaos

Elite dangerous might be an open world space sim?

Elite Dangerous has a Solo play mode in which you can't encounter other players, but it has to be played online and other players' actions still affect your game world. It's also beginning to develop an EVE-style metagame.

Since the OP specified offline play, ED won't do.

@Kryos

Yep thanks. I read up on ED and was hugely disappointed to see the powers that be have just cashed into the online gaming world and lost their heritage. Elite was THE self-contained, free-roaming fighting/trading space sim for the stand-a-lone PC. It should be again. It seems so very wasteful to make everyone expend GBs of data over broadband lines to play a game that a great many would be perfectly happy playing in the comfort of their own home on a stand-a-lone PC or Lappy.

I would LOVE to play ED, but I have no interest whatsoever in playing online with or without a million other wannabe pilots. I want my own space, my own time, to kick-back and immerse myself in a great space sim on my PC knowing it has plenty of spec for the required graphics.

I have been trying Starpoint Gemini 2 and am hugely disappointed. It's not a space sim at all imo. You can't really dogfight anything so it's just a repetitive cycle of letting the ship (crew) shoot ships for you. You press a button to have the ship go from A to B. You press a button to grapple an enemy, another button to commence auto-firing and another button to send over troops. There is no real gameplay here, it's mind-numbingly dull. A real shame.

I may have to try I-War2 but I know I won't like the Newtonian physics it imposes.

Can it really be that difficult for someone to develop an awesome immersive proper stand-a-lone space sim with a fantastic story line, free-roaming element and real pilot control ?

Sigh 🙁

You might want to keep an eye on Nova Voyager http://www.novavoyager.com/ and here http://spacesimcentral.com/ssc/forum/99-nova-voyager/

Should have noted that StarPoint Gemini 2 is a capital ship game so there is no dogfighting as in more traditional games like Elite, freelancer, DarkStar 1 ect.

Cheer for the links Pinback, that looks a promising game.  Here's hoping it comes to fruition and has a great storyline.