Cities: Skylines is a cooperative game based on the popular computer game of the same name by Paradox Interactive.
Gameplay starts with 4 land boards (number can vary depending on scenario). The goal is to finish a number of Milestones and to make the inhabitants of your city happy. At the start of each Milestone one additional board is bought, flipped over from its nature side to its developed side. Players have personal cards that show what they can build, that they discuss with the other players and plan how to best develop the city. The cards show what effects the building will have on the city, for example increasing the need for garbage collection, decreasing crime, or giving a bonus if placed next to a park.
Buildings are cardboard tiles for residential, commercial, industrial and other buildings that have varied base shapes that are placed on the developed boards on the grid.
When the players have developed the city to the next Milestone they will choose which new board to buy to expand the city, score their current happiness, and start a new Milestone. When the last Milestone is finished the game ends, and the total happiness score is added up.
There is only one city treasury, all players add to it when they make money for the city, and take money from it for building a hospital or buying a new board. Making sure you have enough money is an important aspect of the game, if you run out of money you go bankrupt and lose.
A series of scenarios teach the game in steps, with each new step introducing new parts of the game. Each step is easily varied, by for example switching out which Unique buildings are used.