Featured Blog

Thinking About Social Interaction Systems (Or What Middle Earth and Animal Crossing Have in Common)

After playing Middle Earth and Animal Crossing, I noticed they used systems in a social context. This was new to me. So I try to answer, "What are the parts of a social interaction system and how is one different from a dialogue tree?"

A few weeks ago, a friend and I were simultaneously playing different games, he Middle-earth: Shadow of War (MESW) and I Animal Crossing: New Leaf (ACNL). Surprisingly, I began noticing similarities in both games’ NPC interactions. The characters seemed to have some agency and were more aware of the player than the typical NPC – basically, they felt more real. I wanted to put my finger on exactly why they felt that way, so I put together a rough list of behaviors. It was immediately clear the behaviors stemmed from systems rather than being predetermined. I had never really thought of systems in a social context. So, my next questions were, "What are the parts of a social interaction system and how is one different from a dialogue tree?" Answering that turned out to be harder than I expected, but I eventually came up with a rough framework in the context of systemic games.

But before we get into that, let’s briefly get on the same page about systems and systemic games. In Aleissia Laidacker’s much-cited GCAP talk, she explains that a systemic game is one that is comprised of several systems, all of which can influence each other. Systems are a collection of parameters and rules that drive behaviors and outcomes in the game world. In systemic games, these are given agency and turned loose to interact with each other however they want within their given framework. Each system bumbles along reacting to stimuli either from the player or from other systems, resulting in things like NPCs pulling out umbrellas when the weather system decides it’s time to rain.

Interactions Separate from the Player

Social interaction systems are one possible piece of a wider systemic world. They too operate autonomously but are restricted to a social context such as conversing or feuding. They can interact with other systems, like a weather system, by choosing dialogue relating to its outputs e.g., “This rain is so refreshing!” They operate without requiring input from the player. In both Animal Crossing and Middle Earth, it’s not uncommon to find two characters having an interaction entirely separate from you, be it a gift exchange or feudal combat. NPCs interact organically outside of you, and you, as a player, have the potential to witness or even join it, like crashing a war chief battle in MESW to ensure your preferred orc captain wins. They have unique interactions with each other but not necessarily full relationships because they don’t tend to have a running memory of each other.

A Sense of Memory

Memory is an important factor in defining a social interaction system. For both games, characters remember exchanges you’ve had. These interactions layer upon themselves to create a relationship unique to that character. In MESW, this manifests through its Nemesis System. In this game, procedurally generated NPCs ambush you, forcing you into an impromptu battle. When you kill one of the enemy captains, they can spawn again with plussed-up parameters and a death wish for you. They hunt you down while delivering lines of taunting dialogue relating to your inability to kill them for good. The system goes so far as to remember the way you killed them by giving them scars and nicknames related to the manner of death. In ACNL, all villagers start with limited, cordial interaction options but over time they open up new options such as asking you to give them a new catchphrase.

Creating the illusion of memory doesn’t have to be complicated to be effective. What I’ve found in the case of ACNL is that the number of times you interact matters, not necessarily the way you interact. Characters speak cordially at first but warm up over time. Additionally, through smart dialogue, the player is led to feel the relationship is deeper than it is. For example, Gala, a normal-type pig character, asked for a favor which I totally forgot. When I later approached her, she really laid on the guilt explaining how sad she was that I forgot. I felt so compelled to repair the relationship that I sent her an apology letter, despite knowing she would not reference this faux pas again in the future. As a player, not knowing the depth of the system, you begin to attribute more thoughtfulness or feeling to the character than you know you probably should.

Emergent Relationships

In a game, emergence is when an activity (event, problem, solution, etc.) is possible because of the game’s ruleset rather than an intentionally designed outcome. In a nonsocial context, this would look something like using objects in your environment to solve a puzzle in a way that is different from the prescribed solution. In a social interaction context, this takes the form of relationships that were not preconceived. In ACNL, for example, the set of characters that reside in your village is random. They approach you at different times and ask various favors. There are loose rules, such as being asked to catch butterflies only in the spring, but which character makes which request at what time is not planned before it occurs.

Similarly, which particular orc becomes your nemesis is not preordained. If you happen to be bested by one of the many procedurally generated orcs, this sets into motion a chain reaction that makes it increasingly harder to defeat that character even as you level up in the game. This power rebalancing leads to the long-term, protracted conflict with a character that has organically become your nemesis. So, in emergent relationships, the entirety of possibility is not predetermined by designers.

Not a Dialogue Tree (Entirely)

In games, dialogue trees typically handle the social interaction component. In their purest form, you walk up to an NPC, they utter a line, and you choose from a menu of possible responses. Don’t be fooled though; these can get very deep, look at Mass Effect: Andromeda as a single example. You can start romantic relationships with a handful of characters. Here too, memory, or an unfolding relationship, is present. The more you interact with a character and successfully choose the correct romantic options the closer you get to them, eventually coupling off. However, you can only become entangled with the characters that have been designated as “datable.” Every flirtatious advance and coy response specific to that pair has already been planned. Moreover, you never see NPCs interacting outside of the script. In other words, while dialogue trees typically have a sense of memory, they do not afford emergent play, nor organic interactions separate from the player. They tend to rely heavily on the advancement of plot points to trigger interactions.

Conversely, the ability to advance the plot (or even have a plot) is a weak point of systems. Because they are just a loose framework of rules, they have a harder time directing the player. This weakness is why you often see systems and dialogue trees working in tandem. Systems are continuous and omnipresent while trees are continual tools that can guide the player to specific experiences, act as tutorials, or advance the plot.

Next Steps

Admittedly, it took me a bit of effort to delineate between a robust dialogue tree and a true system. While both share memory as an attribute, systems can interact with other systems (or themselves) separate from player inputs, have the potential for outcomes that designers cannot predict, and don’t entirely rely on plot advancement to open up dialogue options. A social interaction system exhibits all of these features within a social context.

One thing I want to think more about in the future is, how can we add improvisation to social interaction systems to make them more dynamic as in Matthew Gallant’s recent article on intentionality and improvisation. I think the Nemesis System did a great job with this with its ambush feature. However, what would this look like for games that are not based on combat but still have elements of social strategy?

Latest Jobs


Playa Vista, Los Angeles, CA, USA
Senior Level Designer (Zombies)

PlayStation Studios Creative Arts

Petaling Jaya, Selangor, Malaysia
Lead Concept Artist

High Moon Studios

Carlsbad, CA, USA
Technical Designer at High Moon Studios

High Moon Studios

Carlsbad, CA, USA
VFX Artist
More Jobs   


Explore the
Advertise with
Follow us

Game Developer Job Board

Game Developer


Explore the

Game Developer Job Board

Browse open positions across the game industry or recruit new talent for your studio

Advertise with

Game Developer

Engage game professionals and drive sales using an array of Game Developer media solutions to meet your objectives.

Learn More
Follow us


Follow us @gamedevdotcom to stay up-to-date with the latest news & insider information about events & more