Computer science researchers at North Carolina State University and Universidade de Lisboa have created a new tool for Skyrim that makes NPCs more autonomous and reactive.

The tool, called CIF-CK, is an artificial intelligence program that uses social behavior models to shape NPC behavior based on how they perceive each other and the player.

The result is a social system that feels more dynamic and autonomous, and one that delivers more instances of unique, reactive gameplay.

"Most games now rely on scripts to govern NPC behavior," explained Arnav Jhala, an associate professor of computer science at NC State and co-author of a paper describing the work.

"In other words, there are decision trees that dictate an NPC’s response to whatever the player is doing. That’s fairly limiting, and means that any two players that make the same decisions will have the same interactions with NPCs.

"We want to move beyond that, to a more immersive gaming experience. And Skyrim was the game we started with."

To develop CIF-CK, the research team expanded on the Comme il-Faut (CIF) architecture model created at the University of California-Santa Cruz back in 2012.

That original model used social science theory to predict how the behavior of one "agent" (or NPC) would affect how others viewed it. CIF-CK incorporates that approach but makes two notable changes.

Firstly, all of the agents in CIF were fully aware of each other, whether the dev liked it or not. Now, CIF-CK gives game devs the power to dictate how much information each agent has, giving them more control over NPC perceptions.

Secondly, CIF tracked changes in how agents viewed each other, but didn't actually translate those beliefs into actions. So, even though an NPC might not like the player, there was no knowing what (if anything) they'd do about it.

CIF-CK, on the other hand, allows NPCs to make choices and take action based specifically on how they view a player, which is a notable step forward.

"This work demonstrates that tools like CIF-CK can be implemented on a large scale," continues Jhala. "We’re now hoping to work with gaming companies and game developers to incorporate the CIF-CK approach into their development processes -- or at least get inspired by it."

The tool has been released as a mod under the name 'Social NPCs' on the Steam Community site. You can check it out for yourself right here.