[Taqwus]

I'd rate it as more complicated than SMAC, which had a very simple combat system and relatively limited resource management and fewer options (e.g. in Dominions, there's a balance to draw between taxes, conventional power, blood slave gathering, research, item forging, global enchantments, gems for combat magic, rituals). SMAC units were, relatively speaking, quite constrained in what they could spend their time doing, and unit interaction was minimal because of the 1-vs-1 non-tactical combat system.
Among games I've played, _Empires in Arms_ might be the only game of similar complexity. For a board wargame, it's quite complicated.