I'd probably call this game a cult classic, but I don't even think the following it has would extend that far. Which is a shame, considering how epic this game is. Honestly I can say if you want a 4X space strategy game, get this, and ignore the sequel.
Why? You might ask, surely the sequel is better! Wrong, it had a terrible, terrible launch, released in a bad unfinished state, to the point where even clicking the new game button would crash it. Which isn't the developers fault, i'd like to add, they suffered the same problem that plague's most games today, the publisher forced them to push it out the door.
But back to the original topic. SotS is addictive and more importantly, fun. Six races to choose from, each with their own quirks and style of play. You can set up a galaxy with a number of options, ranging from amount of stars, to the galaxy shape, the size of the stars themselves, the distance between them... basicaly you can create any game you like and choose who you want to play and play against.
It has a randomised research tree, every game. So don't get comfortable with those awesome beam weapons, come the next game, you might be unlucky and not get that tech. There are some essential techs that every race gets, every game, like the very basic laser or mass driver tree. But each race has different probabilities of getting access to the much more advanced technologies that are in the various trees.
The empire management is... basic, you colonise planets and they develop on their own, terraforming till they are suitable for your race, and building infrastructure. Some planets are so hostile that you can't even colonise them, although there are technologies that you might get access to that can improve the hazard they impose.
Ship design is another interesting and fun part of the experience, as you pick different sections and weapons to put on your ships. Maybe you'd like a ship fully loaded with missles? Sure, go ahead, just be mindful that if the AI has a lot of point defense, that ship will be nearly pointless. So a lot of designing can revolve around what gets thrown against you, or what you come up against.
Then, theres the random encounters... which is an option you can fiddle with in the game settings when you make the galaxy. Basically, it is what it says on the tin, a random encounter can range from a asteroid shower, which can wipe out a new colony, to getting attacked by slavers. But there are special types of encounters, which often turn out to be dangerous and can take massive fleets to stop. I'll give you an example of a grand menace I encountered in a game I played, The Peacekeeper. This dude comes into the map and travels to the center of the galaxy and makes a speech, telling you to stop all hostilities with each other and stop prodcution of war ships. Break these rules while he's on the map, and he attacks you. Sounds reasonable, right? Wrong, this guy is... holy mother of god frightening, he will literally tear your fleets to shreds, no matter what tech you have. Luckily, he doesn't discriminate and will love wailing on the AI as much as you if they step out of line.
All in all, Sword of the Stars is an impressive, and addictive game, that is starting to show it's age graphically, but the fun factor and replayability keeps me coming back to it. I deffinitely reccommend this title to any 4X fans, and especially to space strategy fans. It's an easy to pick up game, thats difficult to master.