It disappeared without any visible explanations. Apparently, it was a a friendly fork of the Breath project (https://github.com/cb-linux/breath) by Apacelus (https://github.com/Apacelus/Apacelus). But Apacelus stopped working on it on May 26th (https://github.com/Apacelus/Apacelus/commit/c84ee94310144ec9...).

There's another project on Github with the same name: eupnea-linux-backup https://github.com/eupnea-linux-backup