Extremely secure utility (use as Library/API or user binary) to determine exact Windows OS build number (major, minor, build, UBR - e.g 26100.xxxx) as required for mission-critical security checks where the developer is limited to usermode. It is very niche, but was also a fun project for me.
Visual Studio: cl /EHsc /std:c++17 /W4 GetWindowsBuildNumber.cpp
It builds from a single code file, headers are defined inside of it (no need for .h) and portability is high.