If you don't know what X² and X³ is, you can check out their respective wikipedia articles.
To give a better description of what the game is like, I'd say that it's what Freelancer could have been if it achieved its full potential: buncha ships, a plethora of customizations, a real economy motivated by buyers and sellers, and you can even have your own station(s). To get an idea of what you're able to do, here's another player's story:
I once "erradicated" the Paranid race. I simultaneously invaded 8 of their outer sectors with 9 fully equipped destroyers and 8 fully equipped carrier ships, each carrying 60 fighters and accompanied by an assortment of smaller support vessels. The nineth destroyer was my personal ship Then I invaded their core sectors. The whole ordeal took 4 hours or so, but by then I had destroyed every single Paranid ship and station in the game. They do respawn after a while, slowly. By setting up patrols within those sectors I was able to keep them down indefinitely though.
The ships were bought from the Paranid, but the weapons were all produced by myself in a gigantic weapon production complex consisting of roughly 50 stations.
That was pretty f-ing epic, but I doubt I'll ever have the patience to go through with this again.
Building the weapon complex and connecting all the stations and setting up transport ships for supply and delivery between this complex and other complexes took at least a week. Getting enough money for the battleships was a whole other issue. For example, 240 medium fighters cost more than you can actually have, the limit is hard coded at 2 billion credits for some reason. I spent weeks buying weapons and selling them to equipment stations throughout the galaxy from the npc stations and supplying them with secondary resources so that they would produce faster, by building stations next to them to fill in supply niches. I had to practically rebuild the entire galactic economy just so that I could buy and sell weapons to get enough money to spent on the fighters.
The other problem was that the game doesn't really have the functionality to assign homebases to the fighter ships in bulk. So, I had to write my own scripts to assign the fighters to the carriers and automatically rename them so that I could identify which fighter belonged where.
I also had used two "unknown" sectors as staging areas, where I had build 9 equipment docks to dock the capital ships for faster refuiling. Aligning these was a huge bitch, so I had to write a script to do this properly too.
Never again (It was fun though)