Yep, yep!

Alyx's physics were genuinely groundbreaking. If this includes all the features they showed off in that game, it'll be one hell of a contender in the physics engine market.

Though it would have been more impactful (ha) if they had released it six years ago alongside Alyx, back when the free physics options were all kind of crap compared to the commercial ones. Jolt has become the de facto free 3d physics solution within the past few years and it's also a huge step up over the old offerings.

Edit: sadly it seems Box3D is based on a stripped-down version of Rubikon and doesn't really do much beyond extend Box2D to the third dimension. I guess its selling point is that it's probably much, much easier to integrate than Jolt, and that the API will be familiar to Box2D users.

This guy made Box2D before, a high performant 2D physics engine that is free and open source and has been used in a shit ton of 2D games. So ofcourse devs are excited with this 3D physics engine. Yes it’s free and open source as well. It’s deterministic across different CPUs, which Unreal’s Chaos physics engine and Unity’s PhysX physics engine are not. This means that simulations with the exact same starting conditions will end up having the same result no matter the device the sim is running on. This a huge benefit for multiplayer games. And benchmarks say it’s performant. Someone already implemented it in Unity and it’s faster than the built in PhysX engine in most cases.

It’s basically a free alternative to Havok. Havok is also a high performant deterministic physics engine, but costs tens of thousands to hundreds of thousands of dollars per game to use. Havok is what many triple A studios use in their games. Like Breath of the Wild uses Havok.

Usually they aren't very good, and proprietary way. This is fully open source and has some really good features like determinism and multi-threaded. It is much more precise and performant as well.

If you check the blog post you can see that the impetus for making this game engine was how buggy Unreal Engine's "Chaos" physics engine was.

Its FOSS. It does some things better, specifically than Unreal. Box2D is quite famous and well supported. Read the blog post if you want to know more details.

Having more options is always good. Box3d uses box2d's api which is familiar for a lot of developers. Box3d also adapts a lot of Erin catto's latest research. He's pretty foundational to game physics, with many physics engines being built off his work and research, like jolt. Box3d is also very fast with a blazingly fast broad phase collision pass.

Also Box3d is one of very few physics engines that simulates proper gyroscopic torques.

Performance mostly

Written in C, not C++, is one for me. I'm writing a little hobby game in C.

It's open source.

Didn't watch whole demo, but one thing: rotational gyroscopic torque

He showed Box3D correctly modelling: https://www.youtube.com/watch?v=1VPfZ_XzisU

And compared it to a game in Unreal when a spinning rifle had an unnatural perpetual motion spinning quality to it

Check out out: https://box2d.org/posts/2026/06/announcing-box3d/

From what I saw: showing a gazillion instances of the same 2 objects.

We're in the diminishing returns part of the curve for almost all technology.

The only small comparison I have seen for now is this thread between Catto and Pierre Terdiman.

for me its C over C++, and the support for crossplatform deterministic simulation

https://github.com/bearlikelion/godot-box3d