An adaptation of a mod for Unreal Tournament, "Killing Floor" is a cooperative zombie-killing game that pits up to six players against a wide and varied horde of mutants. With wide, expansive maps and plenty of gear, Killing Floor encourages players to use their heads when coming up with ways to escape the undead.
The player characters are British soldiers and police officers, sent in after a mutant apocalypse to clean out infected areas. Using a bevy of traditional weapons - assault rifles, shotguns, flamethrowers, and so on - the players must defeat wave after wave of mutant. The map's size and layout is the main tactical consideration of the game; there are five official maps, but each is large enough that players will find plenty of places to hide or hole up. Aiding this is the players' ability to weld doors shut; this prevents them from using it (though they can "un-weld" it), but also keeps the monsters out. In this way, a team finding itself overrun may come to realize that the entrance they barricaded would now be their only way out. Each major area has enough entrances to keep the players on their toes. Health recovery is paced out so that it is reliable, but not frequent; each player has a syringe they can apply to themselves or their allies (though using it on allies heals more). After usage, the syringe takes a while to recharge. Between waves, the players use their money to buy weapons, ammo, and armor at a trader's shop. The shop is only open for 60 seconds, and the location changes after every wave, so players are given a reason to move around rather than stay in one spot. These gameplay choices make the game more active than it might otherwise be - it's easy to imagine every game devolving into holing up in a small room with a single door.
Customization is limited, but present. There are a few models to choose from, but there's little difference apart from the presence or absence of gas masks and helmets. In addition to the player's model, the other main piece of customization is the player's perks. There are six perks that basically serve as the game's "classes". These perks are Field Medic, Support Specialist, Sharpshooter, Commando, Berserker, and Firebug. The Field Medic takes less damage and is able to heal more with his syringe. The Support Specialist welds faster and does better with shotguns. The Sharpshooter does more damage with headshots using rifles. The Commando uses an assault rifle skillfully and can detect certain kinds of enemies. The Berserker takes less damage and does more damage with melee weapons. Finally, the Firebug specializes in the use of the Flamethrower. Each of these "perks" has a level attached to it; by carrying out the main duties of that perk, the powers granted to you by using that perk are increased. This serves as a finely-tuned RPG mechanic for the game, rewarding players for carrying out their roles.
The enemy types are fairly unique and require different strategies. The basic zombie, the Clot, is the weakest and most numerous enemy. Despite its weakness, it can grab a player, rendering them immobile until it is shot off, and leaving them open for another enemy's attack. The Bloat is fat and slow, but can spit acid on a player that will eat through them unless they are healed. The Gorefast has a large blade arm that it uses to slice at players. The Crawler is a bug-like creature whose small size makes him harder to hit in a crowded situation. The Stalker is an invisible woman who closes in on players and then reveals herself to attack; the Commando class is capable of highlighting her at distances. The Siren moves slowly, but her scream does a lot of damage in a large area-of-effect around her. The Scrake is a fairly simplistic enemy; it has a chainsaw for an arm and can take a lot of damage. The Flesh Pound is the most powerful non-boss enemy; if it is shoot too much without being allowed to "cool down", it goes berserk and charges for the nearest player. Therefore, players must manage its temper while still attempting to kill it. Finally, at the end of the round, after all the waves have been survived, the players face off against the Patriarch, equipped with a minigun, rocket launcher, cloaking device, and self-healing. It will take all of the players' combined fire to bring down the beast.
The graphics are probably the game's weakest field. The textures aren't offensive, per se, but they're not dazzling, either; they seem like they're 3 or 4 years behind every other modern game. This isn't really much of a problem in the game itself, since lower graphics means smoother connection and framerates, but in visual terms there's nothing really to look for here. The sound is purposefully campy, with humorous quips from the British soldiers and the trader backed by a heavy-metal soundtrack to encourage the raucous action. There's no chance of the game being mistaken for a tense psychological thriller, not when there's that kind of music involved.
As a whole, Killing Floor is a fun, fairly fast-paced zombie-killing game. The game has few actual "flaws" - it's just low-budget and low-quality. However, the mechanics and gameplay are solid, and even the graphics, while horrendously outdated, have a certain charm to them. If you're looking for a fun game for LAN parties or online matchups, then Killing Floor might be right for you.