For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jcronenberg:git/openSUSE_Tumbleweed/home:jcronenberg:git.repo
zypper refresh
zypper install unbound
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jcronenberg:git/16.0/home:jcronenberg:git.repo
zypper refresh
zypper install unbound
For 15.7 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:jcronenberg:git/15.7/home:jcronenberg:git.repo
zypper refresh
zypper install unbound