It is a true Roguelike game. Turnbased, tactical combat with exploration elements limited by hunger necessitating careful resource management in the form of food, and later torches to manage an increasingly limited range of vision. Consumable items, mostly potions and scrolls, serve as powerful and potentially dangerous utility items quite capable of making or breaking an entire run in a single turn. Runs may last anywhere from a few hours to several days depending not just on how careful you are, but also since it is turn based you can pick it up and put it down at a whim- but be warned! There is no save scumming. If you die, you die.

There are paid versions on steam and the app stores, but also the author of the “Shattered Pixel Dungeon” fork (my personal recommendation) maintains a repository of free and up-to-date versions, though there is some inconvenience messing with the compilations. Regularly updated with balance patches and new content. He’s even a member of this community, and one of the mods: 00-Evan. Well worth the small price of admission.