Para openSUSE Tumbleweed execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby/openSUSE_Tumbleweed/devel:languages:ruby.repo
zypper refresh
zypper install mruby
Para 16.0 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby/16.0/devel:languages:ruby.repo
zypper refresh
zypper install mruby
Para 15.6 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:ruby/15.6/devel:languages:ruby.repo
zypper refresh
zypper install mruby