0 A.D. Alpha 25 Released For This Open-Source RTS Game

[Fidelix]

No.

A good graphics dev could probably port the game in a couple of weeks, and a Carmack-class one could do it over a weekend, but for most people it's simply an unknown amount of time for almost no real benefit, and all of that time could be spent on more important things. (Especially if the original dev has long since left the project, or the rendering code is a trainwreck, etc).

Renderer upgrades for something like this are nearly always unnecessary, and nearly always the result of a developer (typically a newbie to the project) wanting to either scratch an itch or pad out their CV. You may think it's "intensive", but I suspect it very much isn't, other than potentially in terms of drawcalls made. There's a very large difference between "optimizing because we absolutely must have <16ms frametimes and all these effects", and code that's just sub-optimal - especially in an RTS.

(Also, albeit in a minor role: since Apple have chosen to be asstards re graphics APIs (and not for the first time), you'd also need TWO new backends, not one. Again, not a problem for an SME, but an additional hassle for someone who doesn't know the stuff, doesn't CARE about it, and would much rather be working on new pathfinding, or unit behavior, or any of a thousand other things).

Why 2?
There is MoltenVK. It's opensource.