>>1 here, just adding that Ad Astra does not use Newtonian physics, and so it's easy to bring your ship to a complete halt by simply reducing your drive output to zero. This is much the same as in Elite and Oolite (and in fact most space sims I've seen). Unlike those two games, however, in Ad Astra you can not only fly forwards, but backwards as well, which presumably allows for much fancier maneuvering once you've gotten used to the controls. I haven't yet. (´・ω・`)
Having played a bit more Ad Astra, I can say it's quite a fun game, but because of the default controls where pitch and roll are mouse-controlled, aiming tends to be a bit of a bitch. When I try to assist police ships in taking down a pirate, I almost inevitably end up accidentally firing at a cop, and being promptly blown apart as soon as the pirate ship has stopped being a police concern and begun its new life as a salvage target. I have yet to try its joystick control options.
Be that as it may, Ad Astra is an impressive project; even more so because coding it was/is (development has stopped in March 2010, but future features are still planned) apparently a one-man effort. In terms of graphics, while it has a lot more variation in ship shapes compared to Oolite, whose ships are mostly variants of various sizes on a wedge theme (which some OXPs are attempting to counteract), Oolite objects look less pixellated around their outlines. Also the availability of high-res texture OXPs removes Ad Astra's advantage of less bland ship textures. Planets in Ad Astra, on the other hand, are a lot more detailed than their Oolite counterparts, mostly because the game is designed from the ground up to allow certain ships to enter their atmosphere. I have seen mountains, valleys, cities and even oceans in Ad Astra. There is an ongoing project to improve planet textures in Oolite as well as a Planetfall OXP, but even with the highest-resolution textures installed, Oolite planets will never be anything but smooth spheres, and the Planetfall expansion, unlike the Ad Astra system, does not let you pick specific cities on the planet to dock at. Because of Oolite's roots of docking only at space stations, its ships also lack the animated landing gear present in all Ad Astra ships that are capable of atmospheric flight. The 3D all-caps font used in Ad Astra's main menu and Game Over message, on the gripping hand, failed to impress me, rather reminding me of the first Quake instead.
Oolite also does not allow the player to tow derelict ships to the nearest space station; at most you get to scoop up cargo containers left behind by destroyed ships. There is an OXP which lets the player plant beacons on derelicts to summon special giant salvage ships, with which one can then dock and receive payment. This however cannot hold a candle to the tractor beam system in Ad Astra, which you can use to tow any disabled ship smaller than your own into the nearest spaceport, which will then pay you for any cargo left on the ship as well as all salvageable material from the ship's component parts as well.
Some shipwrecks are only too large to tow with their wings left intact, so you can shoot the wings until they break off. This is another thing Ad Astra handles better than Oolite: all ships that I have seen so far in the former game were composed of quite a large number of parts, almost each of which may be damaged and/or destroyed individually. In Oolite, a ship that takes damage will absorb it with the shields first, and if those are not enough it will lose some of the energy in its energy banks, along with a random chance of some frangible ship subsystem becoming unavailable or a random cargo item being destroyed. If a ship's energy banks are completely depleted, it blows up leaving some of its cargo (if it had any) plus maybe a piece of hull behind. (Exploding ship parts in Ad Astra, in contrast, generate quite a lot of salvageable debris.) That's it for most ships, though a few OXP ships have a few external parts that can be shot off without the ship itself exploding.
Can I mention the obvious: EVE Online?
>>4
I have never played it, but what I've read on Wikipedia does not suggest too obvious similarities.
First and foremost, Elite is a single-player game played without an internet connection. All ships other than your own are computer-controlled. Eve Online is a massively-multiplayer online game, with all the social interaction, collaboration and competition between players this implies.
Eve Online star systems are connected by stargates, whereas Elite allows you to travel to any other system within a 7-light-year radius using your ship's internal hyperdrive (or travel to another galaxy using the galactic hyperdrive). I have not played enough Elite to find out whether it is possible there as well (although it should be), but in the remake Oolite ships travelling to another star system open a short-lived wormhole, which other ships can use to follow them without using any fuel, even if they are not themselves capable of independent hyperspace travel.
Eve Online has several playable races (I was unable to find out whether these affect gameplay or are merely cosmetic). Elite, while in theory having many different species, identify the player with the ship he currently owns (only one ship at a time; is this different to Eve?), and the only truly alien race are the always-hostile Thargoids. Also, Eve has a skill-point system whereas Elite relies wholly on the player's piloting and aiming skill as well as purchased ship upgrades.
The economy of Elite is largely static. The market within a given system will have only small fluctuations in the prices on most goods as well as availability of said goods, and these prices do not change depending on quantities of goods imported by the player from elsewhere. Prices and availability are instead determined on whether the system (one planet per system) is an agricultural or more industrial one. I have read that this is not the case in Eve, though I fail to understand the details of its system.
No trading, but if you like general space simulation/exploration then Noctis is pretty fun.
Evochron Mercenary. It's part of a series, and can be played single player or multi (LAN or online).
The version on Steam was bugged - you should look for the trial version or patched version and run that instead (after entering the CD key that was presented by Steam.)