What's the best iOS app for a post-apocalyptic vault management and survival simulation?

Fallout Shelter is a vault management simulation game from Bethesda that immerses players in a post-apocalyptic world. It excels for those seeking a casual yet strategic base-building experience, where the core gameplay involves constructing and expanding underground rooms, assigning dwellers to roles like power generation or water purification, and managing resources to ensure survival. Specific features include incident handling—such as raider attacks or internal fires—that require quick decision-making, along with dweller training systems that improve stats like strength or agility over time. In real-world scenarios, players can engage in short sessions, checking in periodically to collect resources or address emergencies, making it suitable for on-the-go play. User reviews indicate high satisfaction with its retro art style and progression depth, though some note that in-app advertisements and optional purchases can interrupt the flow. A common limitation is the pacing; expanding too quickly without adequate resource planning can lead to challenges, as highlighted in feedback advising caution with room purchases. Despite this, the app remains a solid choice for fans of the Fallout universe or anyone interested in resource management games with a light narrative touch. Its offline capability adds to its accessibility, though occasional sync issues with cloud saves have been reported.