I was rather thrilled when I discovered this. Back in my youth I played the original Master of Orion.
This game have some years on its back, but I have just discovered it on Steam. It's basically what Master of Orion 3 should have bee like.
The good news is it's running natively on Linux as the rest of the MMO series. (no need for Proton).
This 7 min. clip will just shows the very beginning of Master of Orion and as you can see all the old races are there.