For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:Factory:git-workflow/openSUSE_Tumbleweed/devel:Factory:git-workflow.repo
zypper refresh
zypper install gitk
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:Factory:git-workflow/16.0/devel:Factory:git-workflow.repo
zypper refresh
zypper install gitk
For 15.7 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:Factory:git-workflow/15.7/devel:Factory:git-workflow.repo
zypper refresh
zypper install gitk
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:Factory:git-workflow/15.6/devel:Factory:git-workflow.repo
zypper refresh
zypper install gitk