Branch is seeking a Senior Unity Engineer (contract) to work on their new stealth mobile game set in the Castaways universe. Responsibilities include integrating the Adjust SDK for marketing performance measurement, building Apple and Facebook OAuth for user authentication, utilizing the Facebook API for social connectivity, optimizing game performance and responsiveness, and adhering to a test-driven development culture. The ideal candidate will have 3+ years of Unity experience, 5+ years with a modern language like C#, a proven track record of shipping high-production mobile games, and excellent communication skills. The role requires experience in testing, automation, performance profiling, and high-level architectural decision-making.