Para openSUSE Tumbleweed execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:AndnoVember:GNUstep/openSUSE_Tumbleweed/home:AndnoVember:GNUstep.repo
zypper refresh
zypper install gnustep-gui
Para openSUSE Leap 42.3 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:AndnoVember:GNUstep/openSUSE_Leap_42.3/home:AndnoVember:GNUstep.repo
zypper refresh
zypper install gnustep-gui
Para openSUSE Leap 42.2 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:AndnoVember:GNUstep/openSUSE_Leap_42.2/home:AndnoVember:GNUstep.repo
zypper refresh
zypper install gnustep-gui
Para openSUSE Leap 15.0 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:AndnoVember:GNUstep/openSUSE_Leap_15.0/home:AndnoVember:GNUstep.repo
zypper refresh
zypper install gnustep-gui