Imagine a standard idle game: you have a building that produces resources, and with those resources you buy another building that produces more resources, and with those resources, another building, and so on.
Now imagine there's 9 of those games stacked on top of each other in layers and each one has its own set of resources as well as its own prestige resource that supports the layer above it. There's also a limited set of resources you have to thoughtfully allocate between all of these layers. All the while you're aided by Hero, who's crawling through a dungeon full of monsters in search of resources to help you build up the Wilderness, the Village, the City, and what lies beyond...
Other notes: this game is primarily idle. There is no tapping mechanic.