As OGS-6 is a reimplementation of OGS-5 with new concepts and methodologies there will probably never be complete feature parity. We provide binaries of OpenGeoSys-5 ready for you to use. Support is limited but you may ask questions or report bugs via the ogs-users mailing list.
On Windows you may have to install the appropriate Visual Studio Redistributable:
You can get the latest OpenGeoSys-5 (with recent bug-fixes) version from our Jenkins CI system. Binaries for Windows (64-Bit) and Linux are provided for the OGS FEM-simulator under “Last successful Artifacts”.
Source code is hosted on GitHub: https://github.com/ufz/ogs5