We are no longer working on Metro. All the major features have been implemented, so you can try it out if you want, but it is not yet fully stable so use with caution.
Metro is written in C++ and uses CMake. It depends on libgit2 and libssh2 on all platforms, and additionally OpenSSL on Windows and macOS. For detailed build instructions, see the wiki.
See the wiki for details and info.
The latest version of Metro is alpha-1.1. You can download binaries from the Releases page, or build from source as above.
The Windows binaries depend on the Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017 and 2019, which you can download here.
Keep in mind that alpha builds are highly experimental and subject to change. Use with caution at your own risk.