I had three interviews, two with people from Moscow office and the third one - with a person from HQ. All of them were really friendly and professional, their questions were interesting and challenging. I also really liked that interviewers were interested in my gaming experience, that shows that the company is focused on the people who shares Riot's values. I've passed two interviews in Russian, but failed the last one, mostly because I was a little bit nervous and that resulted in forgetting words etc and that made my English even worse than always. Anyway I've got a valuable feedback and felt I was treated fairly. I feel grateful to Riot for that experience.
I liked the whole process, Riot Games is that kind of companies you like even after rejection.