Given that Civilization creator Sid Meier famously defined a game as a series of interesting decisions, it's ironic that the most interesting decision one ever makes in Civ comes before you start playing: which civ will you pick?
Humankind's biggest idea, though it has many, is to ask this question whenever you enter a new era, which you'll do six times over the course of a game. This takes nothing away from the weight of each choice; as in Civ, every 'culture' has a unique unit, city district, and trait, all of which nudge you into a particular playstyle. It's a big deal every time.
Indeed, Humankind's genius is that this decision only gets more interesting as the game unfolds and your circumstances come to bear. The Egyptians are one of my favourite picks in the Ancient era because their pyramids give a huge boost to industry, but prioritising their construction can leave me low on food. Since I need that in order to make people - an important component of any civilisation - I like to opt for the agrarian Celts in the Classical era.
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