Boring but nice
The biggest problem, then, is the story. The plot, such as it is, is made up of garbled, confusing cutscenes that hardly provide any context for the carnage. For a story-based campaign, DS provides shockingly little story. You're aware that you're chasing an evil scientist across a fictional Eastern European country, and that a lot of people have become infected with a virus that turns them into zombies, which tend to rush at you mindlessly, or into mutants, which shoot retro-coloured laser beams out of their hands. As to the nature of the virus, the motivation of the bad guys, or even your own motives for mowing down thousands of generic soldiers and zombies, the plot remains annoyingly vague.
Bits of backstory are introduced but then completely forgotten about, and none of the characters (including the one you play as, Hayden) give you any reason whatsoever to care about what happens to them. For example, a woman who appears in cut-scenes from time to time seemingly despises Hayden, and refers to something that happened in the past as the reason for her hatred. The thing is, you never find out just what happened in this all-mysterious past. The game seems happy to tell you only that Hayden had killed some people because he thought they were "sick", and leaves it at that. Riiiight, so that's why the woman hates me..... It's beyond a joke. I don't expect all games to have Oscar-worthy scripts, but some context or explanation is essential. DS provides almost none of either. Ultimately, It is possible to wrangle some sense out of the story by filling in the gaps with your own imagination and assumptions, but this takes far too much effort over such an unimaginative, uninteresting script. It's like reading every 30th page of a book. You may get the general gist, but nothing more.
Another problem is that DS is one of the most shamelessly derivative games I have ever played. It's 75% Gears of War, 20% Resident Evil 4, with a bit of Half Life 2 thrown in for good measure. The cover mechanics, the vault-and-run, and the aesthetics of the environment are lifted directly out of GoW. The black-market where you purchase weapons, the mysterious virus, and the over-the-shoulder shooting perspective are pure RE4. The only original thing is the glaive, but even that is a direct copy of the bladed weapon seen in the 80s' movie Krull. Still, it's hard to be critical of the glaive, as it's the only thing that differentiates DS from any other generic shooter released this generation.
It's incredibly fun to steer your bladed boomerang of death in slow motion, and amputate a soldier's leg with surgical precision, before decapitating his friend in the same throw. It almost makes the pittiful story forgivable, until you start wondering just why this virus causes a frisbee-like bladed weapon to sprout out of Hayden's hand on your command. You also wonder how a single virus could grant Hayden so many extremely useful super-powers, such as the ability to become invisible, or to steer your glaive in flight. Then you just start wishing for answers again, but the game, of course, never provides them.
The graphics are very competently rendered, but because the game looks and feels so similar to GoW, comparisons are inevitable. And sadly, it's a comparison that comes out firmly in GoW's favour. Both games use a "destroyed beauty" motif, with lots of crumbling architecture and dingy corridors, but DS simply feels less authentic, and therefore not as impressive as Epic's blockbuster. Nevertheless, there was a moment early on in the game, when I put the controller down thinking I was watching a cutscene, but it turned out to be a particularly gorgeous-looking passage of gameplay. A special mention must also go to the impressive prologue mission, which is shown in black-and-white, and provides an intriguing, noirish feel, which the game, unfortunately, completely abandons soon after.
Having said all that, most things in DS work as they should. Melee combat is borderline broken, but this doesn't detract from the overall experience significantly. The controls are very responsive and intuitive. The game is mostly challenging, without ever becoming too frustrating. The cover-and-run mechanic functions well, and the glaive remains fun to use for the duration. A handful of boss battles, as well as a sequence in which you pilot a Mech-like robot, provide some much needed variety.
Unfortunately, the game never really gets into stride. It's all a bit formulaic, a bit dull. Repetitive enemy encounters, unexciting set pieces, and a nonsensical plot conspire to completely destroy the pacing, making certain parts of Dark Sector feel very monotonous. Furthermore, it simply lacks character. It's missing that certain spark that separates great shooters from merely decent ones. But if nothing else, it does provide a moderately enjoyable diversion overall.
The game should take you about 10 or so hours to finish, but there is next to no replay value, so when you complete the story, you'll probably shelve DS, never to think about it again. In the end, it's far from a bad game. It's just not a particularly memorable one.