For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:schaats/openSUSE_Slowroll/home:schaats.repo
zypper refresh
zypper install gcompris-qt
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:schaats/15.6/home:schaats.repo
zypper refresh
zypper install gcompris-qt
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:schaats/15.5/home:schaats.repo
zypper refresh
zypper install gcompris-qt