I've been playing this game for a couple of months now, and since I never saw a dtoid review despite my constant "Aerox get Killing Floor!!", I decided to take matters into my own hands.
Killing floor is based on a UT2k4 mod of the same name, and it's made by the same guys that did Red Orchestra, so I guess that could count as good references. The game is pretty basic, it's mainly a different take on the "invasion" game mode from UT2K4. The main goal in here is to survive a certain number of waves (you can choose between short, medium and long) against a bunch of different types of creatures. As you would expect, each wave gets more difficult than the last, with more and tougher monsters each time. You get money for each kill and some extra if you survived the wave, between these you get a minute to buy weapons, ammo and armor from the trader, some mysterious girl that despite looking at the insanity all around you refuses to open her doors until the coast clear. Once you're done with the waves you get to battle the boss, The Patriarch, which looks really pissed at you for killing his babies.
The game is made to be played with up to 6 persons in co-op, but there are already mutators to get that number up to 32. There are 6 different perks that you can level up, medic, sharpshooter, commando, berserker, firebug and support specialist, each perk can get up to level 5 by achieving certain requirements (like doing X damage with a shotgun or healing X hp from teammates), the perks give you bonus in damage or defense, and also a nice price discount with the trader on certain weapons.
If you think all this will make the game too easy, think again. Killing Floor scales according to the number of players, the more players there are in the server the more enemies you'll get, and even though lvls 3-5 might find Normal a walk in the park, Hard and Suicidal difficulties still prove very challenging, I say this as a lvl 5 support specialist and a lvl 4 sharpshooter.
One of the first things I notice about killing floor was that it came out with very few maps, 5 to be exact, and although they are pretty different, they are clearly not enough. Tripwire announced a new map as free DLC to come out soon (along with the ak-47 and the katana), but meanwhile you'll be glad to know that the mapping community for Killing Floor is insane, just take a look at ]this list, come on, go on, just click it. I guess it helps out that they have a $10,000 grand prize for the winner of their map making contest, but a lot of those maps were there even before the competition was announced and are just getting updated "contest version".
As you might guess by now, the main focus on Killing Floor is the multiplayer content, even though it has a single player mode, the game is waaaaaay more enjoyable when you're playing with friends... or randoms. That's right, from this couple of months i've been playing the game i can say that the community in there is probably the best I've found on any game. It might be 'cause of the scaling I mentioned, or maybe 'cause of the lack of friendly fire, but people are usually willing to help out if they can, be that with money, tips or just covering or healing you.
Before I'm done, for those that might ask, no, this game isn't like L4D, besides the not zombies, the more open scenarios and the fact that you don't just escape, but actually win, Killing Floor has more of a hunter feeling, a "you might be deadly... but so am I!", while still having a ton of "oh shiiiiiiiiit" moments throughout the match.
I called Killing Floor "generic" when I was on Failcast, and I stick by it. Killing Floor doesn't bring anything new, it really isn't innovative, the dramatic slowmotion kills might be overdone and you could get angry when enemies get stuck on a map and you have to go look for them, but It's still only $15 bucks, a ton of fun and by far the game I've played the most this year.
BUY ITand play with me! (At least you Rocky and Aerox).