For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/games/openSUSE_Tumbleweed/games.repo
zypper refresh
zypper install libopenal1
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/games/openSUSE_Slowroll/games.repo
zypper refresh
zypper install libopenal1
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/games/16.0/games.repo
zypper refresh
zypper install libopenal1
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/games/15.6/games.repo
zypper refresh
zypper install libopenal1