@iska The current state of C# is proprietary.

It's impossible to get a working C# compiler from source code (or get it working at all from the alleged source on GNU as I found out). Instead, you'll need mystery meat binaries from microsoft, which are clearly proprietary.

Most binaries for C# software for GNU/Linux seem to be compiled with visual studio on windows, which can output GNU/Linux binaries and definitely doesn't add an extra something (malware) to the binaries.

There was previously one free C# implementation - DotGNU, but that was incomplete at the time and isn't useful anymore.

GNOME released this and made their own C#-like language - Vala.