[nfg]

> Everything that is made with Unity or UE4 uses PhysX

That's not true - UE4 games can be (and are) built against other physics engines.

[aras_p]

Yeah, I should have clarified: most games using Unity or UE4 are using PhysX, since that's what these two engines are using out of the box.

[tokyodude]

Most engines can use other physics engines. People have also used other engines in Unity