Chungking Espresso

Left 4 Dead as Team-Based Rhythm Game

Posted in Game Analysis, Papers, Schoolwork by Simon Ferrari on March 12, 2009

Final section of a three-part paper on Left 4 Dead for a Tech, Design, and Representation class. So much time has passed since when I started writing the pieces and now that it took a lot to muster enough interest to write this. I hope I came up with a decent angle on it, contributing to everyone’s discussion of the emergent qualities of the game. Special thanks to Jon Mills for providing a bit of creative impetus (he’s in the works cited, too).


Left 4 Dead is an exercise in minimalism. Although the levels are fairly linear and player interaction is limited to only a few actions, the play experience changes each time one plays as a result of the machinations of the AI Director. As a cooperative game, Left 4 Dead shares just as much in common with team-based rhythm games such as Rock Band as it does with other shooters and survival horror games.

INTRODUCTION: This article deals with the gameplay of the videogame Left 4 Dead (referred to as L4D). L4D is an important recent artifact in the first-person shooter and survival horror genres. Relevant games in these genres include Half Life 2 and the Resident Evil series, respectively.

Specifically, my analysis deals with how minimalism in level design, narrative, and player control combines with team-based play and a randomized game state (enemies and equipment) in order to cause a cooperative experience similar to the rhythm game Rock Band to emerge. Both emergent gameplay and narrative will be considered. For the purposes of fully exploring the gameplay, I will primarily be referencing the level of complexity inherent in playing on the Expert difficulty level (which enhances the importance of the game’s design).

Minimalism and Flow
One of L4D’s main strengths is its minimalism. Players can basically only shoot, run, crouch, and melee. Inventories are particularly constrained. Most of the levels are linear in nature. Unlike in a lot of shooters, there’s little need to take cover or leap over obstacles; however, within this spare framework a variety of changes to the game state lead to a multiplicity of playstyles and experiences. This exemplifies Lev Manovich’s idea that one of the essences of new media is their variability – that a set of modular elements working together in different ways cause the artifact to be experienced differently by everyone each time it is used (Manovich, 36).

Constrained Player Action
Players move at a constant speed (they cannot sprint, as in some games), which only slows down if they take enough damage. They can crouch to stabilize their shooting accuracy and allow teammates to shoot over their heads without harming them. Unlike some tactical shooters, where a player controls a team of NPCs whose formation they can determine for particular situations, a team in L4D must choose combat formations to fit the given situation and their strengths. The most effective formation for general defense is two players kneeling in opposite directions with the two other teammates standing behind each of them.

One important inclusion is the power of melee. Clicking the left trigger on the controller causes an avatar to swipe crosswards with their gun, knocking Infected enemies backwards. This is particularly useful when a player is overtaken by too many enemies to shoot by themself; crouching and constantly using the melee allows them to minimize damage to their person while teammates shoot off the Horde from a safe distance. A well-timed melee also has the ability to disorient a leaping Hunter or knock a Boomer back to a safe distance for shooting (they explode when killed). Finally, players can click the left bumper button to instantly turn 180 degrees in the event of an attack to their exposed back.

One carries pistols (unlimited ammo) by default, and must choose a single other weapon (limited ammo) from a choice of only two (shotgun or automatic, with the added choice of an almost useless sniper rifle later in the game). Players receive a single health pack at the beginning of each of the 5 levels within a scenario. They will sometimes find one or two more, but usually all one encounters in the field are pain pills (which provide only a temporary boost to health and movement speed). One can also carry either a single pipe bomb or molotov cocktail. Players hold a flashlight, which they can turn on or off.

Level Design and the AI Director
Left 4 Dead’s levels alternate between cramped pathways and dangerous, open spaces. This leads to the creation of a punctuated rhythm that I explain below. Much of the game is wandering down hallways or forest trails, the periphery constrained by darkened offices or dense foliage. Players are the safest during the most linear moments, because they can usually see the direction from which Infected approach them. Open spaces mean multi-directional attacks and a higher chance of being separated.

The game state is controlled by the AI Director, an unseen agent that calculates player performance and varies the state of the game in order to help or hinder progress (by adding items for the players to use or enemy Infected). This artificial agent would satisfy Manovich’s description of a “high-level” AI; its sophistication and contribution to variability in the game state goes far beyond what Manovich observed in early game AI (Manovich, 33). Valve’s implementation of the Director contributes to building the “flow state” in players, a task that usually falls on the level designer.

Mihaly Csíkszentmihályi, a positive psychologist, introduced the notion of flow: a mental state in which one is fully immersed in an experience due to feelings of honed focus toward achievable goals. The game is never too easy, because breezing through one portion will usually mean a Tank or a Witch is about to spawn right around the corner. During more difficult encounters, the game is often fair about the fighting chance it provides you; mistakes on the part of the team, such as brutally damaging friendly fire, contribute much more to failure than the actual challenge presented by the enemies.

Because the task of creating flow has been taken off of level design, the world in L4D acts as a blank state on which players can author and act out their own unique stories (Jenkins, 11-12). Each level draws from a trope of the survival horror genre; thus, these levels constitute “evocative spaces” (Jenkins, 6). This is the essence of Jenkins’ narrative architecture (originally conceived in an unpublished work by Celia Pearce): game design as creation of a space inside which meaningful action can occer.

Team-Based Rhythm
Left 4 Dead is a game about pacing. Compared to other shooters, it is much more about rhythm and teamplay than anything else. The kind of behavior that FPS games usually reward – individual battle prowess – is often inimical to success in L4D. A player who acts as a “Rambo” – the occassionally positive version of a “Leroy Jenkins” – will often be caught off guard by a Special Infected, pinned to the ground, and incapacitated before her teammates can come to her aid.

Pace and Punctuated Action
The best way to succeed in a level is to maintain a steady pace. Backtracking, searching through rooms for items, and standing around to pick off weaker Infected will result in a more difficult experience. Going too fast will result in a breakdown of the team. Weakened teammates move much slower than everyone else, making them easy prey for Special Infected such as the Hunter and Smoker. The most tense moments of gameplay come from guarding a teammate while she heals herself, hoping that the AI Director doesn’t spawn a Horde or Tank.

Play alternates between modes of attack and defense. Players proceed through the level, taking out isolated patches of regular Infected with ease. The only tense moments durin this attack/progress phase come from encounters with Special Infected such as the Smoker or Hunter that can sometimes constrain or incapacitate teammates if not approached carefully with concerted action. Players then must enter defense mode when confronted with a crescendo moment (Horde, Tank, or Witch).

Hordes either come when attracted by a player covered in a Boomer’s bile, at random intervals determined by the AI Director, or at choke points in the level design. Horde crescendos are the most manageable defensive encounters, because players can usually enter a static formation (mentioned earlier) and easily beat back the waves of regular Infected.

Choke points usually feature larger Hordes of enemies, but they’re also typically reinforced by turret positions, barricades, and supply depots. Pipe bombs and molotov cocktails become particularly important during Horde crescendos; the bombs will draw Infected toward them before exploding (useful when the team has become overwhelmed), while molotovs can be used to create defense walls of flame (a pre-emptive measure for protecting the team’s flank).
Tanks require players to enter a focused scatter mode. Keeping too close together will result in the Tank being able to beat multiple Survivors into submission simultaneously, while straying too far apart will allow Hunters and Smokers to pick off distracted players with ease. The Tank will generally pursue the closest teammate. The targeted player must run backwards while firing on the Tank, while her teammates circle the Tank from a safe distance while covering the pursued player’s back.

Witch crescendos uniquely require a stealth offensive/progressive mode of play. Players will hear the Witch crying, and they are usually relatively easy to spot even among throngs of regular Infected. The best option is to sneak around her. In order to do this, players must turn off their flashlights and navigate through the dangerous darkness (light and noise startle the otherwise docile Witch). This leads to an added level of rhythm – that of alternation between light and dark.

More Like Rock Band Than Halo 3
A more fitting name for the AI Director would be “AI Conductor,” because its job is more like leading an chamber orchestra than  a film crew. Levels can be seen as genres of music. You can learn the level (or genre), because the geometry remains the same. But the items and enemies that spawn are different every time, requiring the players to successfully perform a new “song” together with each playthrough.

Because it is a team effort, this game is actually more like Rock Band than a game like Halo 3. In Halo 3, the only thing one can do to help teammates is give them supporting fire. Death means very little, so selfish behavior abounds in the game. In Rock Band, the key to success as a band is to save up “star power” – energy derived from succeeding a particular string of notes. By releasing star power, you can bring your teammates back to life or help them recover from a string of poor notes. It would make it easier for you to save this for yourself, but it doesn’t help you in the end if your team fails out because of one weak performer.

L4D is the same way. Most contemporary (non-tactical) shooters have moved away from the idea of distributing first aid packs throughout a level; instead, a player of a game such as Halo 3 or Gears of War will be able to take a certain amount of damage before needing to hide and regain health. Health packs are the most precious resource in L4D, because the challenege is more one of attrition than individual encounters. Giving one up to an injured teammate means risking that you will be incapacitated in a future conflict, but it strengthens the team overall and gives everyone a better chance at survival.

Emergence, Defined
Janet Murray derides the vague use of “emergence” as a design term as an excuse for laziness and lack of authorial influence on the part of a designer. Left 4 Dead shows that emergence can be structured by careful consideration of level design, artificial intelligence, and randomness. Players are not given explicit roles by the game (the characters are basic ethnic/gender tropes with little personality). They choose at the beginning of each matchmaking experience whether to be selfish or selfless, whether to be a close-quarters fighter (shotgun) or a crowd controller (automatic gun), and whether to be a leader or a follower.

Because the cost of death is so high, it actually means something in this game – something trivially true in real life but usually less so in videogames. Thus, each life-threatening encounter becomes a dramatic moment in which players must quickly decide how to behave. The finale level in a sequence (the fifth) requires the team to hole up in a defensive position against almost insurmountable numbers of regular and Special Infected. When they’re about to be overcome, escape comes in the form of a transport and players must choose whether to make a break for it alone or slowly work through the Horde as a team. These become the most poignant emergent narrative experiences afforded by the game, because all of a sudden all bets are off; sometimes, long-tempered bonds and personal behaviors break down – resulting in real, human tragedy (discussed at length in Mills, Emergent Narratives in Left 4 Dead).

Left 4 Dead pairs a minimal level design and player interaction model with a complex directorial AI in order to allow for an almost infinite variety of play styles and experiences. Unlike in many shooting games, where complex level design controls the flow state of a player, the AI Director in L4D measures player performance in order to help or hinder their progress through the level – maintaining a constant level of energized focus and attainable goals. Players alternate between open and cramped spaces, areas of dark and light, and modes of progress and defense that create a distinct rhythm of punctuated action.

Because of the emphasis on team cooperation (paired with the rhythm previously mentioned), the gameplay of L4D is more akin to team-based music games such as Rock Band than to a traditional shooter such as Halo 3. Like Rock Band – where players are free to perform, show off, and create their own narratives about their band – Left 4 Dead creates a structured space inside which personal forms of play and narrative emerge.

[1]Jenkins, H. Game Design As Narrative Architecture. Henry Jenkins Publications, 2007, 1-15.
[2]Manovich, L. Principles of New Media. What Is New Media? 27-48.
[3]Mills, Jonathan. Emergent Narratives in Left 4 Dead. Academy of Doctor X,


4 Responses

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  1. deckard47 said, on March 12, 2009 at 8:52 am

    You know, I obviously like this series cause I’m such a L4D fan, but I like the idea of Left 4 Dead’s similarities to rhythm games, it really does make a lot of sense. When you see a really together, well-knit team, they keep up a constant temp through the level, never too fast, never too slow. Then again, sometimes its nice to mess around, like you said. Nice to see you on Kotaku’s latest RE5 post btw, that post “discussion” got bizarre fast.

  2. Jonathan Mills said, on March 13, 2009 at 12:29 pm

    I love the idea of exploring the rhythm of navigating 3d spaces and how it is similar to the puzzle aspects of rhythm games; there’s a lot of interesting elements to this piece. You’re spot-on about the AI Composer.

    I’m glad my post was useful. I don’t have too many readers, so it’s very gratifying to find that there are ideas in my posts that can resonate with readers.

  3. News, Kinda « Delayed Responsibility said, on March 13, 2009 at 9:50 pm

    […] Simon over at Chungkingespresso has a cool piece up about Left 4 Dead up. He’s been writing about it for a while, but I haven’t mentioned […]

  4. […] through discrete zones in a level from a generic FPS game. The initial idea for this comes from an earlier essay I wrote for Michael Nitsche last semester, about reading Left 4 Dead as a team-based rhythm game. […]

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