Noisy Pixel writes:
Cities: Skylines owes its existence to a close call. Publisher Paradox and developer Colossal Order, known for the Cities in Motion series, were initially hesitant to proceed with the project. The fear of the revived SimCitys dominance in the market nearly led to the cancellation of Cities: Skylines. However, history had different plans. The troubled launch of SimCity (2013) paved the way for a newer, fresher challenger, so with player feedback from that disaster in mind, Skylines was released in 2015 and quickly sold over a million copies in its first month.
Source: N4G PC Cities: Skylines II Review – Noisy Pixel