This game is surprisingly good. If you are a fan of Resident Evil 4 or 5, or a fan of Dead Space, then you will enjoy this game. Although it is a little rough around the edges, Dark Sector is a gem that is severely underrated.
Gameplay: The game plays like other third-person shooters. It is cover based, so you will spend most of the game with your back against a chest-high wall while bullets fly all over the place. The weapons are pretty standard fare; you have some pistols, submachine guns, and some assault rifles. As you progress, you can find upgrades hidden throughout the levels that will let you augment your weapons at the black market dealer, as well as purchase entirely new ones. The most unique feature of this game is the Glaive, which is more or less a frisbee made out of sharp blades. You gain access to it after the tutorial level, and throughout the game you will gain new abilities, such as guiding it in flight or having it conduct electricity or fire. Guiding the Glaive through the air and slicing into enemies is very, VERY rewarding. Boss fights often center around using the Glaive to exploit a weakness of your enemy. Also, the Glaive can be used to pick up enemy weapons and ammunition from a distance, which is rather nice. As far as exploration goes, the game is very linear, with some puzzle solving here and there.
Story: The story for this game is average, nothing out of the ordinary. You play as Hayden, a special agent who becomes infected with a virus that changes him into....well, you get the point, right? Your infection grants you superhuman abilities, and the Glaive as well. Aside from that, it's a decent storyline that gets the job done.
Graphics: This game looks rather nice, maybe a little dated now, though. The enemies look good, and the envirnments are rather appeasing as well.
Overall, this game is well worth the money. At only $10, it's a steal. If it goes on sale, then you should definitely think about purchasing it. However, you don't have to wait until it's on sale to buy it. If you want a game that is in the same field as games like Resident Evil, or Gears of War, then look no further. It also doesn't just copy and paste those games, but rather it goes in it's own direction.