Deep emergent play represents the ability of a game to provide systems driven experiences. This is distinct from content based experiences, because emergent play comes from the product of systems. These systems will obviously be fed some level of content but unlike a content-driven game an emergent game relies on the interactions between content that come from deeper systems interactions.

Rimworld provides a great example of how this works. For those who are not familiar with it, rimworld is a settlement management game with significant similarities to Dwarf Fortress, in which players attempts to manage a group of Shipwrecked space Travelers on a dangerous world.

One of the reasons why I've chosen rimworld for this case study is that unlike most other emergent games it permits much greater variability in its systems themselves. In a game like Dwarf Fortress, distance, it is possible to add new content. Rimworld permits one to install modifications that alter the execution of game code.

This lets people see exactly what systems are running that they can add into the game. For instance, one mod adds a hygiene need, a whole new system that makes characters' mood dependent on cleanliness and also adds a whole new level of detail in tracking that cleanliness.

One is the things about deep emergent play that divides it from regular play is that there is more information in the player is ready to harness. The various points of interaction between the layers of the game design are so numerous that the game begins to feel realistic even if it relies on significant abstractions.

Minimally Emergent Play

To better illustrate this distinction, let's quickly look at an example of a game that does not rely happily upon emergent developments. It's worth noting that this does not mean that there are no emergent elements, since interactivity itself requires at least some emergence. An example of a game like this would be the classic Mario Brothers game. Not even Super Mario Brothers, which has a greater degree of interaction between maps and characters using more sophisticated rulesets, but the actual original Mario Brothers.

While it relies on a systems driven design rather than content to extend play time, the original Mario Brothers features little emergent play. It has rules which allow for a particular amount of difference in outcome, but the possible scenarios in the end are basically limited to the player losing at different points in the game, as it becomes progressively more difficult, and the actual play itself is limited to just moving the character and interacting with the environment by jumping.

This is not emergent because it will never create an unexpected outcome. There are degrees of complexity that can be achieved, but because it is a single game layer that does not have external interactions it does not offer unexpected outcomes.

A playthrough of a version of the original Mario Brothers game.

Moderately Emergent Play

Next you have a category that I call moderately emergent games. These games have multiple gameplay elements interacting in such a way that an event may be unexpected and novel, but they generally follow highly prescriptive objectives and rarely produce truly unexpected outcomes.

One of the hallmarks of such a game is that there is one particular goal that everyone will follow when they play. There might be optional elements, like challenge modes or achievements and Milestones that players can meet, but the general rule is simply that one will follow a very prescribed path through the game.

I use the example of Brigador for this, which is a futuristic giant robot stomping thing simulator, in which the player is presented with fixed scenarios but given flexibility in how to accomplish their goals.

Really, most modern games fit this category. However, games that are consciously designed to do this typically have a particular focus on system-driven outcomes, like complex AI, open environments, and other systems that are particularly designed to foster this.

Brigador gameplay recorded by myself, with commentary.

Highly Emergent Play

This is a category that has a blurred border with deeply emergent play, but I'd specify it as containing any sort of game which has three of the following criteria or four if interpreted generously (where a deeply emergent game will meet at least four even if conservatively counted):

1. Complex systems that don't require player intervention to function.
2. Mechanisms to turn those systems toward distinctive narrative outcomes (i.e. those that hold psychological valance for the player).
3. Multiple systems interacting with each other on many levels beyond one-on-one contact.
4. Freely defined play goals, with every outcome holding novelty.
5. Opacity of game system functionality to the player.

One of the games that I'd class in this category is the Sims franchise. I think that it has the first two goals and the fourth goal down, but the interactions between systems are relatively limited to central points (e.g. it's a Sim-centric world). Likewise, there's a degree of simplification to many of its systems for the sake of making them more easily comprehensible, though the latter games in the series have gotten increasingly complex and they may be moving into what I call deeply emergent play. I think the fourth point is perhaps the weakest, and sometimes the fifth depending on how you look at it, for the Sims.

Deeply Emergent Play

I'm going to focus on what Rimworld does here to illustrate my point, but this applies to an increasing number of games (like Dwarf Fortress).

Deeply emergent games typically have all five of the above qualities, and you should also be able to see them if you looked at the game as a series of cross-sections.

Rimworld satisfies each in turn:

Complex Systems

Rimworld is in many ways as much of a simulator as it is a strategy game; this isn't to imply that it aims to achieve absolute realism, because it doesn't, but it operates on a level that is independent of player input. Other than being able to define the passage of time and give orders, the player actually doesn't do anything in the game; the events that play out will be different without them giving direction, but they don't make the systems work.

Narrative Outcomes

This is important as a part of emergent play.

Just because something can create complicated events doesn't mean that those events will be interesting.

In Rimworld's case, the subjects get an emotional value attached to them because of their "humanity" and easy associations that can be drawn with them. The colonists go through regular life events, like meeting spouses and growing old, and this happens largely without player input. However, even unscripted things can be interesting. A battle that breaks out while a fire is raising achieves supreme dramatic effect, even though the game probably wasn't intentionally designed to do it (though many random events are guided by AI storytellers who try to throw wrenches in the mix).

The beginning of a colony.

Deep Systemic Interaction

Building a settlement in Rimworld is actually incredibly complicated. In the example above, the settlement sprung up where it did because of two really big conveniences: a pre-built structure that could be converted to a barracks, and the proximity to two geothermal vents for easy power generation. There are downsides to building on the edge of the map as well: it takes longer to get to the all the resources than a centrally placed colony would permit, and enemy raids may spawn uncomfortably close.

This is what a random map can do to influence a colony, but there's even more things going on behind the scenes (presence of water for watermill power sources, growing seasons, proximity to friendly or hostile settlements, etc.) that all relate to a simple choice of location.

Alternatively, one can look at the individual characters in the game. Each of them has a full health system applied (e.g. they can suffer a variety of injuries and receive prosthetics or bionic implants), which ties into their ability to complete tasks. They can also go into good or bad moods, which cause their behavior to change or give them bonuses and penalties. They are sensitive to weather and have needs that must be met.

They are also the player's agents in the game world, which makes the player have to engage with all of these systems, even if it's possible to prioritize one or two at a time. They tend to have holistic interactions, however. Someone throwing a tantrum and hospitalizing the cook means that there isn't fresh food on hand, which may require the person working on the cooling and heating systems to take their place for a bit, which could cause a problem if a cooler malfunctions. Then batteries may get too hot and take out part of the base, causing further issues. It's all capable of creating concrete narrative chains that follow from logical effects that would not necessarily be apparent at a glance.

Freely Defined Goals

Rimworld permits players to work on just building a settlement, fostering relationships with other in-game factions, escaping the planet, or all sorts of other potential goals (like eradicating bandits, for instance).

All of these goals are at the player's discretion; they can choose to pursue them or go about their own business.

Opacity to Players

This is actually where Rimworld demonstrates excellent design that isn't necessarily emergent, because it's very novice-friendly (to such a degree that so difficult a game can be novice-friendly) by giving helpful tips and tutorials as well as a plethora of statistics and information at a glance.

However, there are plenty of unforeseen outcomes, both as a result of the machinations of the AI storyteller and also of the emergent systems. It achieves its sleight of hand by providing so much information that players see the systems and can understand how they work, but all the various elements flow together so seamlessly that they aren't easily identifiable as distinct parts.

Wrapping Up

Emergent play offers some great opportunities to appeal to players and give them an opportunity to explore and experiment, which satisfies appetites for storytelling and unstructured play in ways that more linear games don't manage to achieve.

Using carefully planned interactions between things but allowing them to extend beyond the easily comprehensible is a strength of Rimworld, which gets much of its appeal from having an element of unpredictability and surprising depth to the stories it creates.