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Dan Houser has given fans a peek into the technology behind Grand Theft Auto III.

Just reading that may seem so distant and ancient. Some of you reading this may not have even been born when Grand Theft Auto III first came out.
And for those of you who were that old, Grand Theft Auto III released on the PlayStation 2 on the same year that Conker’s Bad Fur Day released on the Nintendo 64. So it’s old and primitive, even by PlayStation 2 standards.
But it seems that the technology was the secret sauce to what made Grand Theft Auto III the industry changing title that it is.
Dan Houser Reveals Grand Theft Auto III’s Secret Sauce
Lex Fridman asked Dan Houser about what he thought made the game special. We’ll share both Lex’s question and Dan’s response below.
Lex: I think GTA III is probably one of the most influential games of all time. It created a feeling of an open world. What do you think it takes to create that feeling?
You know, there were like these looming skyscrapers. There were the changing traffic lights. There’s the feeling like… First of all, you had a feeling you could do anything, and then the world was… Reacting to it…
Dan: …it wasn’t scripted. It was, it was really, really, really low-rent AI. Like, it was a simulation that you could prod and push and see what happened, and I think that was incredibly…
It was two things. It was the fact that here was a simulation that you could mess about with and the simulation seemed to have a personality. So you could push and see… And the world would push you back to what… in whatever way that meant.
What Is The Secret Of Grand Theft Auto III’s AI?
Before Open AI, before AMD’s Ryzen architecture and Nvidia’s CUDA API, Rockstar’s big breakthrough in Grand Theft Auto III was its AI. And what exactly was in that AI?
We won’t confuse you with the technical details, but in 2001, Rockstar managed to create a finite state machine (FSM) in a video game.
Finite state machines can be very simple. A traffic light, that changes states from red, yellow, and green, is an FSM. Rockstar paired their FSM with a load of rulesets for how characters, and objects react to their open world, to build Grand Theft Auto III’s impressive world.
Because of this AI, civilians knew to avoid you and policemen knew to catch you when you started acting out Claude’s violent outbursts. But really, this all amounted to rules based on cause and effect.
That’s a far cry from the machine learning Gearbox uses to generate Borderlands 4’s 30 billion guns. But of course, there’s a thread that connects this game to that, that we can connect all the way back to the ghost AI of Pac-Man, all the way back in 1980.
