A Valve engineer used ChatGPT to find a new matchmaking algorithm for Deadlock, and now it's in the game

A survey taken late last year found that 31% of game developers were already using generative AI in some way. I'd wager that the percentage has increased significantly since then.

We know Valve is using it: Fletcher Dunn, an engineer who's been with Valve for over a decade, has been posting his "ChatGPT wins" on X, saying today that OpenAI's large language model is an "amazing" tool.

Dunn is more or less using ChatGPT as an advanced search engine, and the interaction that amazed him recently saw him describe a hypothetical kind of algorithm he wanted to use for Valve's MOBA-shooter, Deadlock, and receive an accurate recommendation for a real algorithm matching his specifications. The algorithm ChatGPT recommended is in fact now being used in Deadlock matchmaking, according to Dunn.

"I'm gonna keep posting my ChatGPT wins, because this thing keeps blowing my mind, and I think there are some skeptics who don't get how amazing this tool is," he wrote. "A few days ago we switched Deadlock's matchmaking hero selection to the Hungarian algorithm. I found it using ChatGPT."

Dunn acknowledges that he could have found the same answer with the right Google search terms, but says that the point is that he didn't have to: ChatGPT immediately returned what he was looking for even though he described it vaguely. 

"'Find me this thing that I don't really know the right search terms for, but I will attempt to describe' is just a *killer* app," he said in a reply to another poster. "If it is wrong or hallucinates (which does sometimes happen), you'll figure that out pretty quickly."

This use of ChatGPT reinforces something I suspected when I covered that survey back in January: That scattered instances of generative AI being used to create final videogame art or replace voice actors are really the tip of the iceberg. Mostly, I think developers are using generative AI in ways we aren't going to see directly, such as by using ChatGPT as a search engine, or to write code, or as an administrative tool, or by using image generators during the concept stages.

In January, Steam added a rule that developers must disclose generative AI use when they submit their games, and most of that information is displayed to consumers on store pages. None of Valve's own games feature Steam generative AI disclosures, Deadlock included. Using ChatGPT as a natural language search engine arguably doesn't count as the kind of thing that needs disclosing, though Valve's rules call for developers to tell it about "any kind of content (art/code/sound/etc) created with the help of AI tools during development."

Dunn isn't sure whether ChatGPT will remain as useful as he finds it now. In early September, he predicted that we're in "a ChatGPT golden age," and that the LLM's capabilities will go downhill as training data is lost to copyright challenges or becomes polluted by its own output. For now, though, Dunn says that he permanently keeps ChatGPT open in a Chrome tab.

"I am kind of conflicted because it is often replacing asking the question to another human IRL, or at least tweeting it out to the virtual braintrust," he said. "I guess this is good (the whole point?), but it's just another way for computers to replace human interaction."

ChatGPT maker OpenAI just raised an incredible $6.6 billion in a new funding round as it, as AP reports, turns further toward profit-making. The company claims that its new ChatGPT o1 model is capable of "reasoning" through problems.