Phone interviews with HR, Chief Strategy Officer, Managing Director. Then case study presentation in front of whole office, plus an hour conversation with managing director afterwards. It took nearly two hours for the case study + QA + chat with man. director. Team was very nice.

Several rounds (phone, in person, and video). Everyone (or most roles) does a mock project as a final (or semi-final) round interview that is relevant to the job being applied for. They get a sense of your work, and you get a sense for the job.