[...] how to design game systems, in order to maximize their potential for emergent behavior. Read “Designing Games for Emergence“. Complexity & Emergence, Gameplay Emergence, Game [...]

I totally agree with you Peter, and Rocket-jumping is one of the better examples of how creating even a simple physical simulation can create emergent gameplay situations. I probably should have expounded on Rule 11: Though it is hard to simulate the real world, an intelligent extraction of some of it’s properties (like the damage from rockets, and the kickback of a plasma gun (trick climbing in Quake 3) can lead to emergence.

The interesting question though is, how do we know what properties of the real world to pick? And how deep/realistic should the simulation be? There are simply too many systems around us, and each work at different levels for this to be an obvious choice.

For example, imagine a first person shooter where you (the player) want to liberate a city form a cruel enemy. If I wanted to simulate a human friendly NPC, so they can partake in the game and create emergent gameplay, there are many ways to go about it!

We could simulate one or more of their senses so they react to sound events in the game, e.g. if they hear gunshots coming from around the corner, they could run away from the source!…Or would it be better to simulate their social behavior (e.g. if they are friendly, they ‘hang around’ you)? Or should we rather simulate their goals and ideals (e.g. the NPCs on your side might sacrifice themselves for the cause by positioning themselves between you and the enemy, taking the bullets meant for you!)? These all sound like good ways to go about it, and they all mimic some form of human behavior.

To be honest, I haven’t thought of any straightforward way to pick the right “level” and “process” to simulate, but if you have the resources to implement a number of them, I’d say have a few NPCs with either of the behaviors. Then, invite people to play the game and observe them, to find out what kind of new gameplay emerges, and whether the players find the gameplay interesting, because In the end, emergence is in the eye of the beholder, and the beholders in this case are your players .

An interesting study of emergence. I’d like to add that while the final point about mimicking the world around us is very valid, it can be extended to defining rules that create a consistent game world, but one that’s very different from the real one.

For instance, using an FPS example, with these rules:

1 – Rocket launcher impact depletes health.
2 – Rocket launcher impact accelerates objects away from impact site.
3 – Player can aim weapon in any direction.
4 – Player can jump.
5 – Some reward at a height that’s inaccessible by jumping.

Then the technique of ‘rocket jumping’ (aiming at the ground and launching a rocket at your feet while jumping to gain extra height) to gain a reward (e.g. an item or shortcut) that offsets the health penalty becomes emergent. Clearly not a realistic effect, but consistent within the game world.