For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lkocman:eObcanka:alien/openSUSE_Tumbleweed/home:lkocman:eObcanka:alien.repo
zypper refresh
zypper install alien
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lkocman:eObcanka:alien/15.5/home:lkocman:eObcanka:alien.repo
zypper refresh
zypper install alien
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:lkocman:eObcanka:alien/15.4/home:lkocman:eObcanka:alien.repo
zypper refresh
zypper install alien