UnrealScript

Tim Sweeney wrote the language for Unreal (1998). The syntax sat close to Java; code compiled to bytecode and ran in a virtual machine inside the engine. Two things stood out: state was a keyword, so an enemy could change behaviour by switching state rather than growing a monstrous switch statement, and network replication was declared directly in the language.

That made modding easy, and Unreal Tournament and the Unreal Engine 3 era built large mod scenes on it. But the bridge to C++ was clumsy and the VM slow. With Unreal Engine 4 (2014) it was gone entirely, replaced by C++ for programmers and Blueprints for everyone else.