The interview process takes some time. Riot vets their employees very well for cultural fit as well as competence. The general process for interviews is IQ test, phone interview, possible phone interview #2, and then an in-person interview.
I applied online with an internal referral. I heard back within the week and scheduled the phone interview. The phone interview took about 50 minutes. The interviewer was very tough and grilled me on some talking points but was also very fair.
Shortly after that I was contacted again and asked to come into their offices for a in-person interview. They paid for plane tickets, taxi, and hotel room. The interview was in three stages starting in early morning. Some were a panel interviewing and others one on one.
Be prepared to answer questions about gaming, your history, the company beliefs and aim, as well as behavioral questions.
Overall great experience, HR could not have been more professional.