Rethinking AI behavior in Uncharted 4's vast world

The Uncharted franchise has become synonymous with finely tuned, bombastic set-pieces and expertly choreographed combat sequences.

From the nightmarish submarine escape in Drake's Fortune to Uncharted 3's famous cargo plane crash, Naughty Dog's flagship series has constantly set, and then raised the bar for triple-A action. 

But when it came to designing the latest installment, the studio quickly realized it would have to shake things up. 

As anyone who's taken Uncharted 4 for a spin will already know, the latest entry stands out as the series' most expansive effort. Environments are vast, and teeming with possibilities -- both in an out of combat. 

It's a fact that forced the developer to reposition its gameplay systems, and rethink how its AI combatants should behave and react when encountering the player. 

Searching for inspiration, Naughty Dog began building on the systems it created for its other blockbuster hit, The Last of Us. "[It] really got us thinking about systems," says Naughty Dog game designer, Matthew Gallant, speaking to GamesIndustry.biz.

"It's not that the AI was completely unauthored, but we had interesting AI systems driving AI behaviors for regaining stealth, flanking, and NPCs that could really interact with the environment in lots of interesting ways."

After some tinkering, Naughty Dog soon has its AI searching for players "very efficiently." Yet, as wily as Uncharted 4's revamped foes were behind the scenes, on the surface, they were inhuman oddities. 

"They looked a little lost, or hesitant and undecided. And they also didn't present an interesting stealth challenge to the player," explains Gallant. 

"We had to take a step back and say that the goal of these NPCs searching for the player isn't to find the player. It's to present interesting gameplay, to spread them out in a layout, have them looking human and smart, and moving in ways that are mildly predictable for the player so they have some ability to sneak up behind them."

For more from Gallant, check out the full interview over on GamesIndustry.biz.