That would be something to contact PureOS about. You could open a bug tracker here: https://tracker.pureos.net/ and see what they say, though it seems pretty inactive. They'd have to implement a patch of some kind or get Debian to update the 0 A.D. version in testing (which is what I think PureOS pulls from)
Tough choice
If we’re talking history, I’d probably say Ancient Egypt — advanced engineering, rich culture, and timeless mystery.
If we’re talking gaming, then the Byzantines in Civilization VI — strong religion and siege power, a perfect mix of brains and brawn! ⚔️✨
What about you — do you mean real-world civilizations or ones from the Civ game series?