A game’s interest curve is the roller coaster that maintains the engaging experience. However, the unique moments that remain memorable as proof of the meaningful time players had can only happen when we make a system that can play with itself as much as humans can play with the system.
Emergence is a concept used in game design to describe moments that happen without designers planning them to. A unique scene triggered by the relationship between game and player action, emergence can be achieved by having a big number of elements with simple events that can have their outcome affected in many different ways by other objects, variables and events in the game.
A good example of an element with high emergence potential would be a sphere with real-time physics simulation affecting it. Such an object would be susceptible to all sorts of impacts and the outcome of how far it’d go would depend on the strength of each force applied to it.
Emergence is about the possible interactions versus the amount of events and nuances required to such. One event that only happens in one way, without external variables, is much less emergent than one that depends entirely on the state of the things around it.
My currently nameless (yes, it is still unnamed) top down action game puts players in the shoes of a necromancer. He’s the bringer of chaos. That is what I intend them to feel, and because of it, emergence is specially important.
Demons, which I’ve talked about in the previous article, move waves of Paladins around with their special abilities. The amount they manage to affect and the location they end up at will determine, for example, their next targets (depending on the Demon type, it could be the closest or farthest Paladin, as well as everything around the target).
Then we have Breakable Environment Objects, which take damage as they collide strongly with other objects or are attacked and cause an area effect when their constitution is below 0. Vases apply Fire, which burns and are passed to objects near those being affected. Barrels explode, sending everything flying away to potentially collide with other objects. Fences simply break, but that means leaving an open cliff from which elements can fall to their demise.
There are moments, however, that emergence has to be controlled. This happens to reduce the amount of situations that would compromise your game’s intended experience, such as dominant strategies or undesired exploits. In order to do that, it is necessary to spot the most significant aspect of an event and how affecting other objects could disrupt the system’s intent.
Back to our nameless game, what we don’t want to happen is have the necromancer’s undeads lose their efficiency due to external factors other than human input. They are the safety players have to go in and fight without fear despite all the chaos. It is better, therefore, for undeads to be completely invulnerable to any path manipulation events except for unbreakable walls and ground, which are absolute and block anything. This means explosions won’t send skeletons flying away when the necromancer needs his soldiers to parry the attack of a Paladin.
My book recommendation this time is Emergence in Games by Penny Sweetser.