Too many freemium games are a cheap cash grab. But Bethesda’s mobile spin-off from its famous post-apocalyptic series is that rare beast: free and not constantly squeezing you for cash.

Sharing a scorched-earth setting with the role-playing titles from which it takes its name, a cartoon aesthetic is put to good use in this building game, where players are tasked with creating a vault to protect and attract survivors. Resource collection and management are key – with food, water and electricity needed to maintain the ever-expanding shelter. These are farmed from a variety of upgradeable rooms, which each require dwellers with a different asset – six in all, from strength to luck.

The rooms are bought with caps, earned throughout the game, most dangerously when you send a well-equipped inhabitant into the wilderness to collect weapons, currency and outfits. They can be earned by opening lunchboxes too – either won in-game, or bought, although seeing all that’s on offer without buying anything is easily achievable.

This is addictive, engaging fun and need not cost a penny. A winning combination.