"Fine, obscure gems." Part of a periodical series: Great Games You Never Played.
On the surface, Tripwire Interactive's Killing Floor is a lot like Valve's Left 4 Dead series: multi-player first-person shooter survival co-op with zombies. Except that Killing Floor is actually much deeper than L4D, requiring more tact, strategy, skill, teamwork, and experience to succeed. Killing Floor boasts more enemy types that all function differently, a greater quantity and variety of weapons to use, and a class system that has players performing different roles in the group. To top it all off, Killing Floor has superior "in your face" gunplay that simply proves more cathartic than what you can find in any other co-op zombie-killing game.
The basic gameplay of KF comes down to wave-based map survival. For each match, you're dropped into a self-contained map where you can choose to run around or set up camp in a defensible area. You play through up to 10 waves against the "specimens" (they're not really zombies, they're experimentally-altered humans), with each successive wave adding more enemies and stronger enemy types until you face the boss at the end. You earn money for kills and for surviving the entire round, and in-between each wave you get a chance to visit a trader to buy better weapons and armor.
Launch trailer from 2009. It's been updated a lot since then.
That's the gameplay in a nutshell. It may sound boring and repetitive because you're just endlessly killing zombies, but it proves to be a really addicting game. A lot of variables come into play that make each match feel unique and stimulating, and the learning curve turns out to be its own reward.
First things first: Killing Floor is a hard, challenging game with a lot to learn. There are tons of little nuances to the gameplay that you progressively learn and pick up, which separates a "good" player from a "great" player. When you're just starting out, for instance, you have to learn the layouts of the maps, what the capabilities of the different specimens are, and how the different guns function. From there you have to learn how to prioritize the order in which you kill specimens, how to defend a camping spot, and how to play your role in the team.
The class system (called "perks") allows you to pick a different role, mostly deciding the kinds of weapons you'll use and what your responsibilities to the group are. The Sharpshooter uses precision weapons (rifles, crossbows) to get long-range headshots on strong enemies; the Commando uses automatic assault rifles (like the classic AK47) to clear out weaker specimens quickly; the Support Specialist uses shotguns to deal heavy damage to big targets and stacked hallways; the Firebug uses a flamethrower and other fire-based weapons to slowly burn all enemies; the Demolition uses grenade launchers and rocket launchers to deal heavy damage and cluster damage; the Berserker uses melee weapons to cut down hordes of specimens; and the Medic uses healing darts and syringes to keep the team alive.
Each perk has its own advantages and disadvantages: the shapshooter is essential for killing big enemies, but ineffective at taking on lots of weaker enemies; the commando is just the opposite; the demo does high damage but can't defend himself at close range; the support specialist has long reload times that can get him killed. A successful team relies on a good combination of perks to handle all situations, and on higher difficulties it is essential that each player knows his own role and sticks to it. This is where the teamwork comes into play; it's not just a collection of random people where individual skill determines if the team wins, it's how well the group communicates and cooperates.
For example, every player gets a syringe which they can use to heal themselves or other players. It operates on a recharge-basis, so that every time you use it you have to wait for it to be ready again. Using the syringe on yourself will deplete the entire charge, but if you use it on a teammate, it only uses half as much. In other words, you can heal twice as much/often when healing someone else. If the team is badly wounded, you won't be able to heal up enough if everyone just heals themselves, which places a lot of trust in your teammates.
Likewise, if you're playing a commando or firebug, for instance, and a fleshpound or scrake (the two biggest, most devastating single enemies) comes around the corner and starts attacking you, you have to stick to your job and focus on the weaker specimens and trust your sharpshooters or demolitions experts to save you. If you, as a commando, start firing on the big targets, the smaller ones will build up and overwhelm the team, and odds are you'll only cause the fleshpound to rage (a mechanic where he moves faster and does insane damage when he takes a certain amount of damage in a certain amount of time) and kill you or even the whole party.
The specimens themselves are varied enough to keep everything interesting. The weaker "trash mobs" aren't much of a threat, but they come at you in large numbers and can trip you up if mixed in with stronger enemies. Each one is functionally different from the rest; the clot is slow but can immobilize you, the gorefast sprints at you, the stalker is cloaked most of the time, the crawler is small and jumps a lot, the bloat pukes corrosive acid on you, the siren does an AOE attack on your health (negating armor), the husk shoots ranged fireballs, the scrake wields a big chainsaw, and the fleshpound practically causes instant death against an uncoordinated team.
Killing enemies and surviving a wave nets you cash which you use to buy weapons, ammo, and armor at the trader. The location of the trader changes in-between each wave, forcing you to move throughout the level and plan ahead. Each perk has three or four different weapons they specialize in, with the better weapons costing a lot more, so that you have to save up your cash to afford better guns. But the guns aren't always universally better; a lot of times they just function differently and you'll want to use a different gun depending on the situation. And there's also an option to share your money with teammates, in case one of them dies and has to buy a new set of equipment.
Mix in all of these factors (the map you're playing, where in the map you decide to set up camp, the combination of perks your teammates are using, the weapons everyone is using, and the skill levels of each player), and you get such a wide variety of matches that they each end up feeling fun and interesting. You can often play for hours straight and not notice a hint of repetition.
But the perk system gives you incentive to keep playing, because they level-up as you play. You start out ranked 0 in each perk and can progressively level each one up to 6. Each level brings higher bonuses to your perk, like better damage, faster reloading, bigger ammo capacity, discounts on buying weapons/armor, faster movement speed, better damage resistance, and so forth. Leveling-up then turns into a very satisfying ordeal, much like reaching a new level in an MMORPG.
The perk levels also are largely what allow you to move up to higher difficulties, which themselves prove to be challenging and rewarding. Just as you get the hang of Normal mode, your perks are usually good enough for you to dabble with Hard mode, and once you become an expert in Hard mode your perks are high enough to move up to Suicidal.
The difficulties (especially in conjunction with the perk system) are what really add to the game's replayability. Like with the satisfaction of reaching a new perk, it feels extremely rewarding to move up to a new difficulty level, like you've gone through a rite of passage and are now capable of playing with the "big boys." And each difficulty does enough to make the game harder (by adding more enemies, making them deal more damage, making them move faster, and even changing the mechanics of some of them) that it keeps the game challenging and always feeling fresh and exciting, especially as you learn new techniques to handle each new difficulty.
But despite all of these great features that keep bringing you back for more matches, a first-person shooter would be no fun at all if the gunplay were lame. Fortunately, the feel of using the weapons in KF is absolutely top notch. No other shooter comes close to matching the feeling of carnage and power that you get from wielding a shotgun in KF. Everything about the guns just feels realistic and cathartic, from the brutal recoil, to the resounding audio effects of each gun shot, and to the way specimens lurch with each shot.
Scoring a critical headshot is just the icing on the cake as you hear the sound of bones cracking and watch their decapitated head fly off. The ironsights are also some of the better that I've ever experienced, with the guns actually feeling like you're looking down the barrel of a three-dimensional gun, instead of looking at a 2D overlay.
The Killing Floor community is still active today, usually in the top 25 games being played on Steam at any given time, and often in the top 10 online multiplayer shooters. Tripwire does a commendable job of releasing new, free content for the game which helps to keep it active. Since its retail launch in 2009, we've gotten tons of new maps, new perks, new weapons, new specimens, new difficulties, all for free. Tripwire is also in the habit of having themed events like their Christmas event, a Summer event, a Halloween event, and a Portal 2 event.
With everything said, there's still plenty of life in this game for you to still be able to get into it. It's worth checking out, especially if you're into online co-op shooters.