Divide the land between housing, industry, and commerce. With our without mods and addons, Cities: Skylines allows you to build your own city. Anybody can upload them to the public Steam Workshop directory. The game was originally designed to make it easy for users to develop and share modifications. In fact, any player who seriously enjoys Cities: Skylines, will eventually start experimenting with mods. Unofficial modifications expand the game even more. It may be buildings (you can now build an airport of your own design), natural phenomena, development scenarios (“green” city), and so on.
Each of these expansions adds new elements to the virtual world. Instead of releasing a new series, the creators of Cities: Skylines preferred an approach with gradual modification of the original game, releasing official expansion packs about every six months.
Cities: Skylines was released in 2015 - quite a long time ago by standards of the ever-changing online world, but fans are unlikely to be scared by this.
Cities: Skylines is a competitor and in some ways a successor to the famous SimCity series from the 1990s and 2000s, whose history (so far) ended with a failed release in 2013.