Interviewed for a German office, although I'm from the States. There were various recruitment events for BCG's international offices, and I applied by reaching out to their German recruitment coordinator in charge of the US. The interview process was very simple: two 30-minute interviews with two different Principals from different German offices. Both interviewers were outgoing and interesting to talk to. In both interviews, our conversations took up so much time that we had less than ten minutes left for the case. The cases were simple with basic calculations. After the interviews there was also a written, multiple choice test with various business cases; but I don't believe that it factored into their decision.