For humans, life’s decision trees are virtually limitless. In video games, characters that are so-called “non-playable” now can have more options in reactions.

These NPCs are more life-like – in other words, their reactions are not based entirely on “decision trees” game coders write – thanks to a new tool developed by researchers at N.C. State. 

And thousands of online gamers have already signed up to test the modification tool, or “mod.”

“This is an awesome mod! THANKS!” one posted.

“Awesome idea cant wait for the full version to come out,” added another.

“This mod is focused on improving NPC (Non-playable-character) to NPC interaction and Player to NPC interaction,” explains the site about the mod at the online gaming site Steam.

It’s called CIF-CK.

Players can check out in the popular title Skyrim.

“Did you ever want to play The Sims in Skyrim? Well, you can’t, but this mod is pretty cool,” the creators explain at the video gaming Stream site.

“In short: NPCs in the mentioned locations use social interactions (quests) such as flirting, complimenting, insulting, embarrassing (etc) to interact with each other.

“They try pursue romantic partners and insult those who they feel disgusted by. They try to make friends and introduce themselves to those that do not know them.

“The best part is that YOU can insult them too! Or flirt with them, or ask them to marry you, you choose!

“Manipulate them, destroy their relationships or help them build one, or just wait and see what the end result will be without interfering.”

Arnav Jhala, an associate professor of computer science at NC State is co-author of a recently published paper describing the work. He made headlines earlier this year with work on AI assistants such as Alexa and Siri that he hopes will produce “deeper purpose”.

“Most games now rely on scripts to govern NPC behavior,” he told Matt Shipman of NCSU News Service.

“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.”

NCSU researchers worked with colleagues at Universidade de Lisboa on the mod.

CIF-CK is an artificial intelligence program that utilizes social behavior models to make NPCs more reactive and adaptable to players’ behavior.

Jhala has big hopes for the mod.

“This work demonstrates that tools like CIF-CK can be implemented on a large scale,” Jhala said. “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.

“And, of course, we’re always working to make AI more expressive and capable of further enhancing the game-playing experience.”