Time is a key element of the Civilization games. As you advancing through the various stages of history dictate what technology you have and what you are able to do. However, aesthetically, the days and nights don’t change on screen. The only exception is through the Wonder movies. However, as Brian Busatti revealed to IGN, this could change:
“We’ve been experimenting. We’d also like to do a setting where you literally you see the sun rise when you start the game. But we’ve also had a setting where you can just keep rotating through. It doesn’t make sense to tie it to turns, but a looping two or three-minute cycle. And we also want to give people the option to set certain times, just say ‘6pm!’ and play that way.”
Busatti also says a feature like time-of-day lighting could find other purposes. “There are plenty of ways to tie it in for the modding community. I could see someone making a Gettysburg game where the time of the day actually indicates when the game’s going to be over. So you start your battle at sunrise, and it gets incrementally darker every turn until it’s night time, and that’s the end of the game.”
Civilization VI comes out October 21st.