FOCS is very new and still under heavy development; there have not yet been any versioned releases. To obtain a copy of focs, either clone or download the master branch of the focs repository (located at https://github.com/quytelda/focs.git). For example:
$ git clone https://github.com/quytelda/focs.git Cloning into 'focs'... ... $ cd focs
All commits and tags are PGP signed as of 2018/5/1. You can have git show PGP signatures on individual commits using
git log --show-signatures. All releases will have a corresponding tag, which is signed using GnuPG.