For those looking for something new in the space sim genre, it may be best to look elsewhere.
What sets this game apart from the rest of the pack and it became the game's major selling point, is the ability to customize your ship. A word of warning though, the customization opportunities are nowhere near as intuitive as they are in games like Spore and Galactic Civilizations II. It's very similar to how Star Wars Galaxies allows you to trick out your ship. Basically, you start with a chassis, pick which armor you want, add a few guns along with some missiles and you're set. That's it. You can't alter the colors of your ship, change the positions of the weapons or do anything of the sort. A lot of potential was squandered here and it's a serious letdown. To be honest though, it isn't too big a deal. If you're the type who'd rather not spend their time worrying about which setup is better, the game comes with some preset loadouts such as fighter, bomber and assault fighter, which helps streamline the process some. After you pick out something you like, you're ready to go.
There are some plot twists and curves during the course of the game, but it's pretty much expected if you're a veteran of the genre. As for the combat, I found it dull and uninspired. It's just like everything else out there except for one thing maybe: the ability to change combat modes. To do so, all you have to do is raise or lower the temperature output of ship which can easily be performed at the touch of a button. Lower your temperature far enough and you gain the ability to stealth through space undetected, but at the cost of speed and damage output. On the other side of the spectrum is Corter mode. Here your ship moves at top speed and can fire much faster, but this offensive prowess comes with the cost of your shields. It can help spice things up, but you'll usually find yourself going all out in the heat of battle rather than stealthing about during the thick of it. As you fire your weapon or engage the afterburner, you'll raise the temperature of your ship inevitably forcing you into Corter mode anyway. It's an interesting spin, but the options lose their appeal after the first few missions.
My biggest complaint of all lies with the game's sound. It seems that in the developer's efforts to effectively capture what it feels like to fly around in space, that they hindered the overall experience of the game. The only sound you'll hear is the occasional explosion, when you fire your guns and when you engage the afterburner. That's it. You don't hear other ships fire or anything and half the time I had no clue what was going on because there was no sound in the background. Music was fairly uninspired and often times you didn't hear it. Voiceover work was alright and the dialogue was pretty funny at times as it doesn't really make much sense. One line was, "I am looking into their minds to eradicate their souls!" Or something along those lines. Needless to say, I laughed pretty damn hard.
While Dark Horizon isn't the greatest thing since sliced bread, it is by no means a poor representation of the genre. If you're looking for something new and ground-breaking, don't expect it here. If you just want a good ole fashioned space sim, Dark Horizon fits the bill.
Copy/pasted from my main review here: http://www.411mania.com/games/reviews/86161/Dark-Horizon-(PC)-Review.htm