In the CryENGINE, not all animation needs to be driven by bones. The engine supports animating hard body geometry, which can be far more optimal for certain assets and in certain situations. You might want to animate complex scenes such as the destruction of an object in 3ds Max and then export that to the engine, or you might simply want to open the door on a vehicle—all this can be done using rigid body geometry animation.
Animated hard body geometry data only supports directly linked objects and does not support skeletal-based animation. It is composed of two file types:
.cga(Crytek Geometry Animation)
Let's creates some rigid body animation: