Level 4.5: Emergence

Emergence

Another dynamic that game designers should be aware of is called emergent gameplay (or emergent complexity, or simply emergence). I’ve found this is a difficult thing to describe in my classroom courses, so I would welcome other perspectives on how to teach it. Generally, emergence describes a game with simple mechanics but complex dynamics. “Emergent complexity” can be used to describe any system of this nature, even things that are not games.

Some examples of emergence from the world outside of games:

• In nature, insect colonies (such as ants and bees) show behavior that is so complex, it appears to be intelligent enough that we call it a “hive mind” (much to the exploitation of many sci-fi authors). In reality, each individual insect is following its own very simple set of rules, and it is only in aggregate that the colony displays complex behaviors.
• Conway’s Game of Life Links to an external site., though not actually a “game” by most of the definitions in this course, is a simple set of sequential rules for simulating cellular life on a square grid. Each cell is either “alive” or “dead” on the current turn. To progress to the next turn, all living cells that are adjacent to either zero or one other living cells are killed (from isolation), and living cells adjacent to four or more other living cells are also killed (from overcrowding); all dead cells adjacent to exactly three living cells are “born” and changed to living cells on the next turn; and any cell adjacent to exactly two living cells stays exactly as it is. Those are the only rules. You start with an initial setup of your choice, and then modify the board to see what happens. And yet, you can get incredibly complex behaviors: structures can move, mutate, spawn new structures, and any number of other things.
• Boid’s Algorithm Links to an external site., a way to simulate crowd and flocking behavior that is used in some CG-based movies as well as games. There are only three simple rules that individuals in a flock must each follow. First, if there are a lot of your companions on one side of you and few on the other, it means you’re probably at the edge of the flock; move towards your companions. Second, if you are close to your companions, give them room so you don’t crowd them. Third, adjust your speed and direction to be the average of your nearby companions. From these three rules you can get some pretty complex, detailed and realistic crowd behavior.

Here are some examples of emergent gameplay:

• In fighting games like the Street Fighter or Tekken series, “combos” arise from the collision of several simple rules: connecting with certain attacks momentarily stuns the opponent so that they cannot respond, and other attacks can be executed quickly enough to connect before the opponent recovers. Designers may or may not intentionally put combos in their games (the earliest examples were not intended, and indeed were not discovered until the games had been out for awhile), but it is the mechanics of stunning and attack speed that create complex series of moves that are unblockable after the first move in the series connects.
• In the sport of Basketball, the concept of “dribbling” was not explicitly part of the rules. As originally written, the designer had intended the game to be similar to how Ultimate Frisbee is played: the player with the ball is not allowed to move, and must either throw the ball towards the basket (in an attempt to score), or “pass” the ball to a teammate (either through the air, or by bouncing it on the ground). There was simply no rule that prevented a player from passing to himself.
• Book openings in Chess. The rules of this game are pretty simple, with only six different piece types and a handful of special-case moves, but a set of common opening moves has emerged from repeated play.

Why do we care about emergent dynamics? It is often desired for practical reasons, especially in the video game world, because you can get a lot of varied and deep gameplay out of relatively simple mechanics. In video games (and to a lesser extent, board games) it is the mechanics that must be implemented. If you are programming a video game, emergent gameplay gives you a great ratio of hours-of-gameplay to lines-of-code. Because of this apparent cost savings, “emergence” as a buzzword was all the rage a few years ago, and I still hear it mentioned from time to time.

It’s important to note that emergence is not always planned for, and for that matter it is not always desirable. Here are two examples of emergence, both from the Grand Theft Auto series of games, where unintended emergent gameplay led to questionable results:

• Consider these two rules. First, running over a pedestrian in a vehicle causes them to drop the money they are carrying. Second, hiring a prostitute refills the player’s health, but costs the player money. From these two unrelated rules, we get the emergent strategy that has been affectionately termed the “hooker exploit”: sleep with a prostitute, then run her over to regain the money you spent. This caused a bit of a scandal in the press back in the day, from people who interpreted this dynamic as an intentional design that glorified violence against sex workers. Simply saying “it’s emergent gameplay!” is not sufficient to explain to a layperson why this was not intentional.
• Perhaps more amusing was the combination of two other rules. First, if the player causes damage to an innocent bystander, the person will (understandably) defend themselves by attacking the player. Second, if a vehicle has taken sufficient damage, it will eventually explode, damaging everything in the vicinity (and of course, nearly killing the driver). These led to the following highly unrealistic scenario: a player, driving a damaged vehicle, crashes near a group of bystanders. The car explodes. The player crawls from the wreckage, barely alive… until the nearby crowd of “Samaritans” decides that the player damaged them from the explosion, and they descend in a group to finish the player off!

As you can see, emergence is not always a good thing. More to the point, it is not necessarily cheaper to develop a game with emergent properties. Because of the complex nature of the dynamics, emergent games require a lot more playtesting and iteration than games that are more straightforward in their relationships between mechanics and dynamics. A game with emergence may be easier to program, but it is much harder to design; there is no cost savings, but rather a shift in cost from programmers to game designers.

From Emergence to Intentionality

Player intentionality, the concept from Church’s Formal Abstract Design Tools mentioned earlier in this course, is related in some ways to emergence. Generally, you get emergence by having lots of small, simple, interconnected systems. If the player is able to figure out these systems and use them to form complicated chains of events intentionally, that is one way to have a higher degree of player intention.