Grand Theft Auto is the franchise that defined the modern open world, letting us steal cars, ignore traffic laws, and occasionally play ball with Roman. For people like me, Vice City is more than just a nostalgia. It’s still baffling that underneath all the spectacles, there is still some tangled web of ridiculously clever (and sometimes insanely stupid) code that makes the whole experience feel enjoyable!
In this edition of Geekswipe, let’s talk about the weird, nerdy things Rockstar did to make these worlds feel alive for us.
The driving physics
I’ve complained enough about Watchdog’s rigid driving physics. Part of that comes from the GTA experience. Especially GTA IV. Turns out, the cars in GTA didn’t just have mass and friction, they also had meticulously programmed suspension geometries.
If you had loaded a trainer and explored the cars, you might have encountered these settings. What Rockstar did is they essentially built a rudimentary vehicle dynamics simulator inside the game. Every single car had unique values for dynamics like roll center, damping, and spring stiffness. Each car had its own chassis physics.
Only if Ubisoft is this smart!
The Euphoria engine
Speaking of physics, let’s talk about how people die in the game. In older games like Vice City, characters just triggered a pre-rendered death animation.
Starting with GTA IV, Rockstar integrated NaturalMotion’s Euphoria engine. This gave the developers a standard above the basic ragdoll physics. Euphoria used simulated biomechanics and a central nervous system to make character models react dynamically to their environment. You shoot a guy in the leg, he grabs it and stumbles.
And the interesting thing is, it’s also behind the other masterpiece of a game, Max Payne 3.
The sniper and the moon
In GTA Vice City, there’s a weird interaction involving the moon. If you shoot the moon with a sniper rifle it changes size.
Okay, that’s a cute Easter egg. But the reason it exists is absurd. According to legend (and some deep dives into the game’s code), the developers couldn’t agree on how big the moon should be. So, instead of making a final decision, a developer tied the moon’s scale to the weapon impact system. Shoot it, it toggles through different sizes. They built a physics interaction in the skybox to solve an office argument.
Traffic lights are real
Ever noticed how annoying the traffic lights are in GTA V? That’s because they aren’t just random red or green toggles. They operate on actual logic systems that mimic real world traffic engineering.
The game’s code manages traffic flow based on intersection density. Major arteries get longer green lights and smaller side streets get shorter ones. The game actually tracks the volume of cars waiting at a red signal and adjusts the timing dynamically, much like smart traffic grids in modern cities.
