I know this isn't terribly helpful, because I'm not sure what I'm really looking for, so I guess I'm asking for some suggestions of what games might be worth trying out. I realize the inherent issues involved in this request, because the ancient world tended to develop at a MUCH slower pace and was at a much smaller scale compared to later eras and trying to make this engaging/fun isn't nearly as easy as other, later time periods.
I mostly play RPGs and Strategy.
1) Imperator: Rome (Paradox Interactive)
Part of their Stellaris / Hearts of Iron / Europa Universalis / Crusader Kings family. Sure, they're all different, but they're all kind of the same, too. If you've played any of them, you'll know what to expect.
2) Field Of Glory II and Field Of Glory: Empires (Slitherine / Matrix Games)
Field of Glory I & II are tabletop-style turn-based wargames set in ancient to early medieval era - pretty good for that sort of thing. The devs recently made FoG:E as a grand strategy game. Similar idea as but won't be as polished as Imperator: Rome. I think you can export the strategy map battles from FoG:E to FoG II if you have both. Fight the battle in FoG II, and then export the results back into FoG:E. Cumbersome, but gives you a sort of Total War experience with turn based tactical battles.
3) Slitherine/Matrix are probably the top wargames dev/pub company around, although they do other strategy games. They'll have plenty of ancient era setting stuff. Quality, complexity and polish may not always be top notch, but that's indy games for you.
4) Age of Decadence. This is a fantasy RPG, but it's very heavily based on ancient Rome.