I don't know about game libraries in particular, but in general, it's pretty common for C++ libraries to ship with a C api, and for most non-C++ languages to us

I don't know about game libraries in particular, but in general, it's pretty common for C++ libraries to ship with a C api, and for most non-C++ languages to use that as the basis for their integration. It looks like several (https://code.google.com/p/bullet/issues/detail?id=43 https://code.google.com/p/bullet/issues/detail?id=43) people (https://github.com/bulletphysics/bullet3/issues/130 https://github.com/bulletphysics/bullet3/issues/130) have written C apis for bullet already, for that reason. Vala, .NET, LuaJIT and Rust all get mentioned.