Killing Floor Cooperative Design
Every single system within the Killing Floor franchise has been designed around cooperative play.
From the first wave to the last boss, the enemy will scale based on how many players are in the party. The perks available to the players will create a specific role for each player to fill, and the money that is earned during the previous wave(s) is usually spent in consideration of the rest of the team at the trader phase.
The maps themselves are also designed to encourage the formation and communication of teams as well. As time passes, it is evident that the franchise is less concerned with individual player performance, and more so with the "group rhythm" of the players working together.
Cooperative play is not something that is layered over the top of the gameplay. Cooperative play is literally what defines the gameplay.
The replayability of the franchise stems from the foundational elements of the franchise which include the ability to play through multiple difficulty levels (in terms of wave counts), multiple perk trees that allow for progression of the player characters, and the variety of maps that can be played through.
Built for Six Players
Killing Floor 1 and Killing Floor 2 were both designed around cooperative sessions of up to six players. The structure of the games is simple, and involves a team of players surviving a predetermined amount of waves of enemies, then earning money from the kills they have achieved and preparing for a boss fight.
As each wave progresses, the number of enemies and their overall health increases. The pace of the game increases as well. Additionally, mistakes made by the players will become increasingly difficult to correct as the waves progress.
How the Design Works
One thing that allows the design to work effectively is the use of scaling. The number and health of the Zeds (the enemies in the franchise) will vary based on the number of players in the party.
For example, a single player experience will feel restricted and tense, whereas a six player experience will feel chaotic. Large enemies like Scrakes and Fleshpounds will demand coordination when the team is at maximum capacity, due to their increased health pools and rage mechanics that will require a coordinated effort to take down quickly.
The trader system promotes working together. During the breaks between rounds (waves) players are rewarded for their efforts with cash (dosh). Players can then decide to share some of that cash.
An experienced player may contribute more cash so a teammate can purchase an improved version of a weapon sooner. While the amount of money shared by players may seem insignificant, it can have long-lasting effects on teams. The most common outcome of teams working together financially is that they tend to establish themselves at a quicker pace.
Players are also able to communicate financially during boss fights. Boss fights; such as the Patriarch from the first Killing Floor and Dr. Hans Volter from Killing Floor 2, require coordination among players to complete successfully.
Both of these boss battles require players to work together and coordinate their movements, who needs to target whom and provide medical aid if needed. If a team does not coordinate their movements while battling against either of these bosses they will be overwhelmed and the battle will become very difficult. However, if a team works together and coordinates their movements the boss will be much easier to defeat.
Perk Roles and Team Identity
Another important aspect of Killing Floor's cooperative gameplay is the perk system. Each perk offers a unique and defined role for players within the game.
Within the first Killing Floor game, players were able to choose from six different perks, which also included roles like:
- Medic
- Support Specialist
- Sharpshooter
- Commando
- Berserkers
- Demolitionists
The second Killing Floor game added several new perks and skill trees for players to explore and customize.
Each perk in the game earns experience points by performing specific actions. Medics earn experience points for healing teammates, Support Specialists earn experience points for using shotguns and welding doors, etc.
The perk system creates a direct link between the individual advancement of the player and the overall function of the team.
A Medic that ignores his teammates' need for healing will advance more slowly than a Medic that continually heals his teammates. Likewise, a Support that chooses to ignore assisting with door control will weaken the team's ability to hold defensive positions.
The addition of skill trees in Killing Floor 2 allows for even greater customization options. At predetermined levels, players are able to choose between two skills that define how they interact with the rest of the team.
For example, a Medic can choose to focus on increasing the strength of his healing or improve the offensive capabilities of his team. A Berserker can choose to increase the length of time he remains alive in a fight or increase the amount of damage he can inflict upon his enemies. The choice of skills affects how each perk interacts with the team.
A well-rounded team typically consists of a player that provides crowd control, a player that provides precision damage, a player that provides healing and a player that can deal large amounts of damage at close range. When all of these roles are represented in a team, waves tend to flow more smoothly.
- Medics will help to restore health and provide buffs that will steady the team during heavy waves.
- Supports help to manage close-range damage and control doorways with welding mechanics.
- Sharpshooters will focus on precision shots to disable large Zeds before they overwhelm the group.
- Commandos extend team awareness by revealing cloaked enemies and sustaining mid-range fire.
- Berserkers absorb pressure at the front line and maintain space when corridors collapse.
- Demolitionists specialize in explosive damage that clears dense clusters of enemies.
When too many players have the same role or there are gaps in the roles available to the team, problems occur. For example, if a team consists mostly of close-range perks, they will have difficulty dealing with ranged threats.
Players develop an identity based upon the type of perks they have obtained. This identity will influence the overall composition of the groups that you are part of. Most squads will develop a consistent mix of a Medic and Sharpshooter, as well as other roles which will create a sense of familiarity among all members of the team, creating a personal sense of what your role is in relation to the rest of the team.
Difficulty Levels and Escalation
Replayability within Killing Floor is directly related to difficulty level. There are many different levels of difficulty that exist within the franchise including Normal and Hell on Earth.
As you progress through these different levels of difficulty, the amount of damage that the enemies take and inflict will increase along with the health of the enemies and the aggression of the enemies. In addition, there is an immediate consequence when you make a mistake at the higher levels of difficulty.
When difficulty levels increase, the way in which your team communicates will also change. At lower levels of difficulty (normal) you can get away with having your teammates scatter out while you fight off the zombies.
However, at the higher levels of difficulty (Hard and Suicidal), you will need to be very coordinated if you want to survive. At the highest level of difficulty (Hell on Earth), it will almost seem like your teammates are always "on" and aware of what is going on around them.
These increased levels of difficulty will encourage you to continue playing. For example, a team that has mastered the Hard level will probably move up to the Suicidal level. Once a team has mastered the Suicidal level, they will probably attempt to master the Hell on Earth level just for the sheer challenge of doing so.
Even though the same maps are used throughout the entire franchise, the same maps will feel much different when you are playing at a higher level of difficulty due to the fact that the enemies will force you to hold onto a position much tighter and execute your plan of action much cleaner.
Increased levels of difficulty will also help to show the synergy of your perks. For example, a Sharpshooter's ability to freeze large Zeds will become a vital part of your strategy. A Medics ability to give his teammates resistance buffing will be the determining factor as to whether or not he and his teammates will live or die during heavy waves. As a result of this, the game will reward the teams that develop strategies that work together and will punish the teams that rely solely on raw firepower. For example:
- Enemy health and damage output will begin to increase significantly with each difficulty tier.
- Large Zeds will spawn more frequently on Suicidal and Hell on Earth.
- Healing efficiency becomes more critical as incoming damage scales upward.
- Mistimed reloads and poor positioning are punished more severely at higher levels.
- Ammunition management is a team responsibility.
Since the difficulty level will affect the mechanics of the game rather than the actual layout of the map, the maps will be able to stay relevant regardless of the level of skill that a player uses. For example, a hold that works on the Normal level of difficulty may completely fail on the Hell on Earth level of difficulty. As such, players will need to adjust their positioning and the way in which they manage their resources.
Wave Structure and Rhythm
Wave systems are consistent across the entire franchise. Within each level of difficulty, the players will survive a certain number of waves before facing a boss. With each new wave, there will be more enemies and larger enemies introduced into the fray. The tempo of the waves will gradually shift from manageable skirmishes to long periods of sustained pressure.
What will keep the waves interesting is the rhythm of the waves. During the early stages of the waves, players will have the opportunity to explore the environment and build up their resources. As the waves continue to grow, the mid-stages of the waves will introduce large, powerful enemies that require the players to be focused and working together as a cohesive unit. Finally, the later waves will compress both the time and the area available to the players, requiring them to constantly communicate with one another in order to survive.
The Enduring Appeal of Cooperative Survival
The core of the Killing Floor experience has remained consistent in both primary entries. As such, the fast paced action of the game combines well with the need to think strategically and work as a team.
The difficulty curve allows players to play through the game at their own pace while the ability to customize characters with perks provides a wide range of play options that can be utilized to create a variety of experiences all within the same structured framework. The map rotation in each entry also creates a new experience for the player, yet still maintains a level of familiarity throughout.
The cooperative gameplay loop is very easy to follow; survive waves of monsters, help your teammates during the battles, develop and adapt your battle plans, face the boss monster, and repeat the process again with an even better plan.
Players are able to replay the Killing Floor series due to the ability to refine their skills. They test out new build combinations of the many perks available, they try to beat the highest levels of difficulty, and they experiment with how to best utilize the various holds available in the game. The structure of the game is solid and dependable, thus allowing the player to rely on it, while the flexibility in how the game can be played allows for a great deal of variation.
Ultimately, it is the cooperative nature of the Killing Floor experience that defines the franchise far more so than any one gun or monster. It is this understanding of the value of shared survival that keeps players returning to the Killing Floor series time after time.
With each game session, players create their own mini-story based upon how well they communicate and collaborate with each other to overcome the challenges presented by the game, which is what draws them back to the series, not just for the excitement of the spectacle, but for the constant challenge of having to rely on each other in order to overcome the overwhelming odds present in the game.