Cities: Skylines' first expansion pack 'After Dark' will release worldwide on September 24.
The expansion brings a day/night cycle to the city-builder and nighttime city services to the game and it will cost around £10 (only confirmed as $14.99 in the U.S at the moment.
There will be less traffic during night time, which means that you'll be able to "identify problem areas in the road network" and send your workmen to fix things while it's quiet.
"This ebb and flow of traffic will make the city feel more alive and add a whole new element of trying to cater for both the quiet times and the busiest times," said lead designer Karoliina Korppoo. "New options for public transportation allow you to choose if the lines are active during the day, night or both. Creating bus lines that serve the needs of citizens only during the night, when their destinations are different from the day, is possible and a very good strategy."
Cities: Skylines is PC only at the moment, however it is eventually coming to Xbox One and possibly PS4.