A Hitman developer says GTA 6's NPCs are ten years ahead of the industry

Berkay Dursun, an AI programmer at IO Interactive who worked on the crowd technology in 007: First Light, says Grand Theft Auto 6 is at least ten years ahead of the industry on non-player characters, and he's going purely off the public footage.

The context helps, because this didn't come from a press release. He was replying to a post that had compared Grand Theft Auto 6's crowds unfavourably with Hitman's, and his answer was that the two aren't the same kind of thing. In Rockstar's game every character is simulated individually, where a Hitman or Assassin's Creed crowd is mostly bodies running repeating movements with no schedule or behaviour underneath them.

Why his opinion carries weight

Developers praise each other's games all the time and most of it's professional courtesy. This one carries more weight because of who's saying it.

IO Interactive makes Hitman. The whole Hitman design rests on crowd simulation and NPC behaviour: routines that repeat believably, characters who notice things, disguise systems that only work because strangers judge what they're looking at, and levels that are basically clockwork machines made of people.

No studio has spent more of the last twenty years thinking specifically about how background characters should behave. Dursun works on exactly that problem, and his own game's crowds are among the best in the business, so when he says a rival's a decade ahead he's conceding something on the one subject he's best placed to judge.

Look at what IO isn't saying, too. Nobody there is calling the graphics or the driving a decade ahead. The compliment's narrow, and it's aimed at the hardest problem in the genre.

Why crowds are the hard problem

Rendering a hundred people is a solved problem. Making a hundred people look like they've got somewhere to be isn't.

The failure modes are familiar to anyone who's played an open world: pedestrians who walk into walls, who repeat the same four lines, who react to gunfire and then forget within seconds, who pop in behind you, or who exist in a bubble twenty metres wide and stop existing outside it. Every one of those is a budget decision and not an oversight, because simulation costs more than animation and the crowd's the biggest thing on screen.

What Rockstar seems to be spending on instead is persistence and specificity: characters who are individually authored instead of assembled from parts, and who keep behaving when you stop looking.

It matches Rockstar's own account

It sits right alongside what Rockstar has said about the work: over 600,000 animations and a Los Angeles team of writers, directors and producers built solely to bring non-player characters to life.

That team's the detail I'd pick out. Most studios don't hire writers for background characters. It suggests the crowd's being treated as part of the cast, the way you'd treat actors instead of props.

It matters for how the game plays as well as how it looks. The wanted system uses witness descriptions as evidence against you, and a witness system's only as good as the simulation of the people doing the witnessing. If a bystander's a prop, being seen means nothing. If a bystander's an agent who saw a face, a jacket and a car, being seen is the whole game.

One developer, one trailer

This is one developer's read of a trailer, offered in public and not on behalf of his employer. It's informed opinion about marketing footage, not a technical teardown, and trailers are put together to look their best.

Crowd behaviour is also exactly the sort of thing that degrades under load. A scene built for a trailer runs at a density and level of scripting that a live open world, at sixty simultaneous systems, may not sustain, and Rockstar hasn't committed to a frame rate that'd tell us how much headroom there is.

So it's worth hearing because of who said it. It still isn't evidence.