While we are all waiting for Nexus, next kodi major release, I'll share some news about solus kodi build, currently Matrix.
At our development tracker there was a report about missing input-stream-adaptive addon some-time last month. And the root cause was that upstream, which provides retroplayer implementation, switched to Nexus branch for development. Package build succeeded, I missed important upstream change, and because of that past kodi package has been missing addons. The solution was to disable retroplyer addons, until Nexus is released. That's why you may have experienced rather large kodi package update recently, since it included standard addons like it used to be.
Nexus is currently is at its alpha stage (internal testing) and it's definitely takes time to have a major release like kodi. So, if you use solus with a TV in your living-room (look, ma, no keyboard!), RetroArch is another retroplayer implementation you could substitute kodi for your retrogaming needs. Once Nexus is GA, I'll re-enable retroplayer addons and kodi emulation addons are going to be back.