A game deserving far more recognition than it gets.
For its time Elite was ground-breaking. The AI of the other ships makes this game so absorbing you almost feel like your not playing a single player game and actually a huge MMO. While travelling through space you see other ships, some simple traders, others pirates wanting your precious cargo and GalCop flying in formation enforcing the law, you often see ships involved in their own battles, being escorted by the police, mining etc.
Elite never forces you to play in any particular way, its entirely down to you on how you'll reach the 'Elite' ranking, you can trade and take down pirates, or become one yourself, its up to you. Elite's game world is also pretty massive. Eight galaxies each containing 256 planets, you'll never run out of places to visit.
ArcElite is a classic, its a shame not many people have heard of it.