Simple gameplay but addictive

A game where you play as a monster and defend your dungeon from enemies. The initial goal is to survive for 100 days, with the ultimate goal being 1000 days. After 100 days, you can reincarnate to obtain stones that unlock features, allowing for idle play. Since you can collect gems by leaving the game idle during times you can't touch your phone, like while eating, bathing, or driving, it's a recommended paid app.