Obviously there is a demand for a great city builder. Colossal Order sold 500.000 units of Cities: Skylines so far as you can read on Twitter:
"Looks like we broke the 500k barrier, HUGE thanks to every single Chirpy who has supported us so far! <3"
Now the developer Colossal Order is working on the first patch to solve problems like a black screen when starting the game, cloud upload bugs, an inactive new game/load-button and the poor performance on Linux systems. Regarding the gameplay, the developer wants to implement a better traffic simulation and business and commerce should be influenced by parks.