Para openSUSE Tumbleweed execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/X11:windowmanagers/openSUSE_Tumbleweed/X11:windowmanagers.repo
zypper refresh
zypper install i3
Para openSUSE Factory ARM execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/X11:windowmanagers/openSUSE_Factory_ARM/X11:windowmanagers.repo
zypper refresh
zypper install i3
Para 15.5 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/X11:windowmanagers/15.5/X11:windowmanagers.repo
zypper refresh
zypper install i3
Para 15.4 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/X11:windowmanagers/15.4/X11:windowmanagers.repo
zypper refresh
zypper install i3