Versions and useEdit
Avalanche Engine 1.0Edit
Used in Just Cause.
Avalanche Engine 2.0Edit
See also File types in Avalanche Engine 2.0.
Avalanche Engine v?Edit
Used in Just Cause 4.
JC4 is said to be using a specialized version of the Apex engine that has all sorts of weather related extra features to be able to run sandstorms and tornadoes.
JC3 developers talking about the Avalanche Engine and how it's been improved since JC2:
JC4 developers talking about the Apex engine: