"Newer" isn't necessarily better or more productive. Especially given the monumental task of having to write a game without the benefit of any of the libraries developed over the past few decades.
Perhaps the reason there are no other viable options is because C++ is pretty well suited to the task?
Why would you have to lose the libraries? .so files are .so files; it doesn't matter what language they were written in, as long as they expose an API that can be cleanly wrapped by your own language.
... and a standard ABI, otherwise you will never be able to link. C++ did not have standard name-mangling conventions until recently, which forced you to use the very same compiler to compile both your libraries and your own code. This is still unfortunately very much a concern with all these legacy systems out there. Your only solution is to expose your API as a C library or distribute your source code.
Perhaps the reason there are no other viable options is because C++ is pretty well suited to the task?