Paradox Interactive have confirmed that the first expansion for their hit city-builder Cities: Skylines will be released worldwide on September 24.

After Dark is an appropriate name, because the expansion is adding day and night cycles, something that will likely add a bit more realism to the city-building simulator. For citizens who have a little too much fun, the addition of prisons will sort things out – while new taxi mechanics will help nighttime revelers get around efficiently and safely.

“Taking the cities from daytime to night is not as simple as one might think”, said lead designer Karoliina Korppoo.

In After Dark, mayor-players’ in-game cities will go from day to night and back again, and their bustling burgs will look – and behave – differently.

Overall, the expansion has brought a new texture layer to each and every building in the game to have the windows light up nicely.

The After Dark expansion will be available to all current owners of Cities: Skylines for $14.99. Also there are new lighted signs, neon signs and other lights to make the city look interesting during the night.

To give curious city constructors a glimpse of what awaits them in After Dark, Paradox has released the first weekly design diary from Cities: Skylines developer Colossal Order, along with a new batch of in-game screenshots showing several of the substantial sundown surprises that await players. “The sun rises and sets, painting the sky with bright colors, you can see the moon and stars move across the night sky”.