EXPIRED Freebie | Fallout Shelter (for PC & Xbox One) | Windows Store
It doesn't mention anywhere for how long this is going to be mahala so I'll just let it default to expire in 45 days time.
Description from the website:
Fallout Shelter puts you in control of a state-of-the-art underground Vault from Vault-Tec. Build the perfect Vault, keep your Dwellers happy, and protect them from the dangers of the Wasteland.