Linearity and Emergence are foundational concepts to game design. To have a gameplay experience in the first place, players have to have some degree of control or way to influence the gamestate. Our focus now is on the ways the player can influence the game in pursuit of the goal. Some games force players to execute a sequence of actions the same way every time. Other games give the player more freedom to reach the goal through different sequences of actions. While it may seem easy, truly understanding how complex and nuanced linearity and emergence are and how they converge in game design will take nothing short of all of the concepts and terminology developed on this blog thus far. With this article series I'll be as straight forward as possible while exploring the many branches of this topic. Sound contradictory? We'll see.
A Bit of History
Simply talking about linearity in games is tricky because it's relative. Moment to moment the experience can be one way, but from here there are ever larger organizational structures that can be analyzed. In other words, a challenge can be linear or non-linear as well as a level, world, act, area, or the game overall. When we don't clarify the level of organization that we refer to when we make statements about linear or non-linear gameplay, the communication either becomes vague or bogged down with clarifications. I think a bigger reason we have trouble talking about linearity in games is because video games are the newest medium of entertainment at the end of a long line of popular linear mediums. Like books, plays, and movies we often find it useful to describe certain video game challenges as being linear (whether they are truly linear or far from it). The fact that video games borrow from these other mediums doesn't make things any easier to understand.
While the medium is new, at the same time games are ancient. Games and gameplay are so familiar to us that I think we tend to overlook how emergent they are. We ignore just how non-scripted and non-sequential playing basket ball is, for example. We think of this kind of emergent gameplay as normal, and we sort of zoom out to the next higher level of organization to analyze. How else do you explain why many gamers feel the single player campaigns of games like Call of Duty are linear when there is a lot of variation to the challenges and ways to vary the sequence of moment-to-moment player actions? Put it all together and we very easily have a problem on our hands. Now people are very confused about what linearity and emergence is, how it works in gameplay, and how to talk about it.
New Definitions
As you probably know, I'm a stickler for language. I want everyone to be able to express their ideas and opinions clearly. Doing so requires using the same terms or a clear language. It also requires cleaning up terms overloaded associated with too many meanings. From my experience, "linear" and "emergent" are now overloaded terms. Linear is often used with a negative connotation. Emergent is used to describe happenings in games that developers never intend (a troublesome trend that I discuss in my article Emergence You Can See). And both terms are used to describe a range of other specific game design concepts.
Take this quote from Ryan Payton creator of République at Camouflaj; "We are committed to having a deep, non-linear, dynamic, sandbox gameplay. No point-and-click or FMV-like gameplay." It's clear that Ryan made this response to clarify that his upcoming game features the kind of gameplay where you actually play a character in scenarios as opposed to just watching the action play out with minimal player interactivity. Pay close attention to how Ryan makes this clarification. "Deep" is a troublesome word that I'll tackle in my next article series. So let's focus on this string of adjectives: "non-linear, dynamic, sandbox." Describing the game this way is a bit redundant and confusing. Can a game be linear and dynamic? Can a game feature sandbox interactivity and gameplay simultaneously? Can you see how knowing precise definitions here would be useful? I offer these definitions:
Linear gameplay is playing a challenge or a series of challenges where there is only one possible sequence of gamestates due to player mechanics that will result in victory (or progression toward the only outcome with the game defined positive value). All other possible gamestates are fail states or inconsequential in progression (to the goal) or the difficulty of the gameplay challenge. Also referred to as "linear level design."
Emergent gameplay (or non-linear gameplay) is playing a challenge or a series of challenges where there are multiple (at least 2) sequences of gamestates due to player mechanics that will result in victory (or progression toward an outcome with a game defined positive value). Having multiple sequences, ways, or possibilities to pursue victory also means that a player cannot experience all the possibilities on one attempt. Also referred to as "emergent level design" or "non-linear level design."
Key terms to note in my definitions are "gameplay" and "mechanic." My definitions are designed around a very clear definition of gameplay that is distinct from interactivity. My definitions are framed around gameplay challenges which are defined by gameplay goals. With a gameplay focus, we can rule out actions like moving a cursor around in an Advance Wars menu from consideration because this action simply doesn't affect the gameplay challenge at hand. And limiting our analysis to mechanics and how they affect gamestates, we can rule out hacks, some glitches, and other odd abilities some have found to sequence break. My definitions fall within the domain of gameplay, which consists of, on the smallest level, single gameplay challenges. Note that I use the word campaign to refer to the progression of levels across an entire game.
Conflation and Correction
What makes talking about linearity and emergence in level design particularly difficult is that in most cases we're dealing with degrees of non-linear gameplay. We all recognize that some games have more options, are more complex, are more dynamic, and are more open than others. Yet simply trying to pin down how non-linear these games are requires a more exact design analysis, and this is where many fall short. The definitions I presented above are great for identifying examples of linear or non-linear gameplay, but this can only take us so far. If you take an entirely linear campaign and add one small branching path at the end, technically the campaign is non-linear. I bet most gamers have a problem accepting this. At least, this example is not what many have in mind when they use terms like emergent, open, or even sandbox.
When many say a game is non-linear, they may mean the gameplay is dynamic where various gameplay mechanics, actions, and elements interact with each other in meaningful ways; that the gameplay is deep offering several back-and-forth counters of your mechanics as you gain advantages; that the game features interesting choices with a range of options that the player is informed about where no one choice is the best; that the game can have multiple solutions where there are multiple conceptually distinct or uniquely challenging ways of achieve victory; that the game has multiple goals; or that the game has alternate paths offering different areas the player can take to reach the end.
So which of these additional terms do many commonly conflate with emergent or non-linear gameplay? Some? All? In what combination? It's hard to say, but I suggest that we separate these terms from the concept of non-linearity. Keep non-linearity a very broad descriptor and then use these terms to further describe gameplay. I can understand why many have conflated these terms so much. The truth is most of these terms cannot exist in linear games. They can only be found in emergent gameplay. Still, to be clear, we shouldn't use "emergent gameplay" or "sandbox" as a substitute for these terms. Our ability to communicate is severely crippled when we try to convey such complex design concepts into such a broad and relatively simple term like "non-linearity."
With your mind cleared and set on what linearity and emergence really are, we can continue our investigation of why these concepts matter to game design. Next, I want to present video game examples to help solidify this foundation.
In part 2 I'll present lots of examples of video games on a scale of most linear to least, organized by genre.