For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:expeehaa:crystal/openSUSE_Tumbleweed/home:expeehaa:crystal.repo
zypper refresh
zypper install shards
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:expeehaa:crystal/16.0/home:expeehaa:crystal.repo
zypper refresh
zypper install shards
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:expeehaa:crystal/15.6/home:expeehaa:crystal.repo
zypper refresh
zypper install shards