Killing Floor is a fantastic game to play with friends, but the game struggles when you take it online.
The basic idea of Killing Floor is that you have to kill zombies, or specimens as they are called in the game in order to get more money. This money is used to purchase new weapons from the trader, whose location always moves around the game, until you get to the boss at the end of the level. It's tried and true,and it's fun to boot.
The co-op elements to the game, while not as integral to the game as they are in say, Left 4 Dead, for example, are certainly there. Each player is equipped with a, for a lack of a better word "medic injector thingy" which players can heal themselves, or other players with, and a welder, which allows them to seal off doors, buying them some time to escape from an onslaught of specimens.
This is all well and good if you are playing with people you know, but when you just hop onto a random server, you'll often find yourself pretty much deserted, and that's not by a lack of players, but by the fact that teamwork is pretty much nonexistent in Killing Floor. In Left 4 Dead, teamwork is essential, because if you roam out on your own, and you get caught in a hunter pounce or something like that, it is out of your control to save yourself. While there are various types of specimen in Killing Floor, none of them, except possibly the fleshpound, a particularly gruesome creature with buzzsaws attached to his hands, require any teamwork at all to take down.
A skilled player can easily run through a map with virtually no help from his teammates on some difficulties, and unlike in Left 4 Dead, there is actually a legitimate reason you might want to play like this. The perk system, while certainly a breath of fresh air in the co-op zombie killing shooter scene, probably harms the game as much as it helps. Unlike in other games, the perks in Killing Floor give you ridiculous advantages if you take the time to level them up, and while the process of leveling up these perks varies, they are almost always things that hinder the teamwork factor.
For example, the sharpshooter perk, requires you to get several headshot kills with certain weapons to level up. And these numbers arent chump change either. You're going to need to kill thousands and thousands of specimens if you want to level up all of your perks to the maximum level of 6. And while the perk system does offer replay value, you have to wonder if the game would just in general, be better without it.
Unfortunately, that is pretty much all the game has to offer. While $20 seems to be a fair price for a game like this, and I'm sure many people have gotten more than their money's worth of fun out of the game, you get very little in terms of meaningful content out of the box. There are about 7 or 8 maps to choose from in the base game, and while they are all well done, they do get old VERY quickly. I'm sure for some, who take the time to learn all of the map's intricacies will have a greater appreciation for the maps than someone like me, but if it were not for the very active mod scene, then I think its safe to say that the multi-player wouldn't be anywhere near as populated as it is today.
And about that mod community, Tripwire treats the mod community with open arms, to an extent. As far as I'm aware, Killing Floor is the only game in existence to have something called whitelisting, which was added in as a patch. So from searching the official forums for a bit, it seems as if Tripwire was angry about a number of "exploit" maps, which gave players the ability to level up their perks very quickly. The best comparison would probably be achievement maps in Team Fortress 2. So, in a move, which I consider absolutely ridiculous, but you can make up your own mind on that, if you have a custom map that you want players to be able to level up their perks with, you have to actually send it in to Tripwire and get it added to their master list of all maps approved to have stat tracking. That means, that if for whatever reason, you either don't want to send your map in, or you can't, your map is permanently crippled, and a good portion of the community will NEVER put it on their servers, because you can't level up perks on it. While I realize that Tripwire has the right to do whatever they want with their game, I think that this is taking it a bit too far.
So, if you're reading this review, you've probably already seen the game a bit. It's not the prettiest game in the world, but it isn't too bad looking either, and the voice acting is definitely within the "so bad it's good" range. So yeah, the production values aren't particularly high, but as the game is still running on the Unreal Tournament 2004 engine, this isn't particularly surprising.
So, overall, Killing Floor is a pretty good game. If you happen to catch it while its on sale on Steam, then go for it, if not, I can see the game being worth $20 to someone who just can't get enough zombie slaying, but for the average gamer, its probably a bit too high a price to pay for what you get.