Century City is an okay idle game where you build a city and spend time by tapping in a mine to get more money to build you city. It's not the worst idle game I've played ever, but it's a bit boring. There isn't much to do besides tapping inside the mine - and sometimes playing some very simple mini-games - so it didn't grab my attention for super long. The isometric style is kinda cool, however.
Your city is a bunch of buildings that give you money each second, and you build more buildings and upgrade them in order to get more money to make more buildings. It's the typical loop of idle games, except that it feels kinda slow and there isn't much to do in the city while you're waiting for your money to come in. Buildings don't have many applications and nothing happens while you're idling there, so far the only building that I had seen with anything to do was the casino where once a day you could play a dice game of guessing high/low, but even then, it was only once a day.
Tapping in the mine is the most involved part of Century City, you tap to break blocks, and you tap a lot. You can pay premium currency to tap automatically, you also can sometimes find treasures that start a minigame of tapping at a right time to get cash or auto-tap items. There are a few things you can upgrade for the mine but beside the pickaxe, everything is more or less cosmetic. I kinda wish they had added some other types of upgrades to the mining section, maybe some very slow automatic mining, or a chance to critically hit the blocks and break them faster.
I don't have much more to say about CC, it's an okay time waster, but there is so little to do in it than the game part is very small and inconsequential.