I love this game. It is a little bit challenging to work out some things but the game provides lengthy tutorial scenarios (the campaign), 26 other scenarios varying in difficulty and an endless mode - there is also an encyclopedia you can access but it isn't necessarily all that helpful.
Each scenario has a main objective and there are optional side quests. You have to build houses, markets, a supply chain for goods for your citizens and/or for trading at the market. You also have to build barracks, guard towers, things to entertain the citizens and cope with natural disasters. There is also a research ability.
I have been having a lot of fun working out the best strategies for getting my city up and running and continuing to run. This is a game that will keep you occupied for quite a while.