It's the deepest game you could find in the world. It has fluid, smoke simulation, emotion/feeling/stress simulation pathfinding based in goals, jobs and needs, organs and injuries, lots if plants, many many rock type, A WORLD GENERATION WITH THE HISTORY, CIVILIZATION AND PEOPLE SIMULATION!
You have two modes : Fortress where you have to manage a fortress by only marking job zones or orders and dwarves, if the Jon is turned on for they, will do them ( or not, maybe they'll eat, sleep or fight with another dwarf). You have to manage the whole fortress, the many industries, their happiness and then eventual sieges or hidden beasts you could dig into.
The adventure mode is more closer to a roguelike. You take control of a human/dwarf/elf(tree humper), and you'll do oretty much do what you could do : ask for quests, bring then head of the target, beat the village with said head, drink citizen's blood, lick the severed head, etc... You can explore whole world with that character, if you can survive.
Learn and dive into Dwarf Fortress.