Gamma is a synthesis toolkit by Lance Putnam and it’s an open source software.
The source code is available on github

I compiled it for my project and I’ll write it down how I set up my MS VC++ 2015 on Windows 10 environment for Gamma.
Gamma requires two external libraries, one is libsndfile, the other is port audio.
Since I’m not interested in playing back sound files, I just avoided to include libsndfile.

Port Audio
Port Audio is very popular cross platform audio I/O kit and it’s downloadable from the website.
I basically followed this instruction and compiled it on MSVC 2015.

Then, I got portaudio_x64.dll and portaudio_x64.lib files under portaudio/build/msvc/x64/Release

Link portaudio to Gamma
Gamma provides a detailed instruction for the build on Windows. So I just made one C++ project and place all relevant Gamma .cpp codes downloaded from the git and setup a path to

/portaudio/include
/Gamma

in properties->C/C++/Additional include Directories

Then, set portaudio_x64.lib

under Linker->Input
and also set the path to .lib

under Linker -> General -> Additional Library Directories

Then, copied the portaudio_x64.dll to the directory of exe and run the project.