Kingdoms Reborn isn't exactly a tiny game, but while it did sell some 300 thousand copies, it was still "only" 300k. It is a true citybuilder to every level, very deep and engaging.
Its eras are well developped and allow you all the way to hiting rocks on stones to post industrial electrical nations moved by sweat, oil, air and sun.

While that on itself isn't exactly impressive, the fact that it does so while simulating well over 20 thousand walkers on a maxed out game while being multiplayer without issues that cracks my eggs.
I played multi-session 40+ total hours games with 12 players without more than three or four desynchs, due to playerside issues.

Warfare isn't the point of the game but the solution to warfare is fine, being it mostly a clash of resources, as there are no actual units to be controlled, just points to be designated and assigned.

It is a great experience by itself for a citybuilder, specially with how decently deep it can get. But once played multiplayer with a dozen people it becomes a life changing one, at least as far as games go, and i wish every citybuilder could do it.