I was an employee referral and was very excited about the whole endeavour. Having a degree in computer science, I always dreamed of joining a top gaming company.
The interview process moved fairly quickly for me... about 6 weeks to get through the whole thing and it was like an endurance test comprised of a total of 11 interviews; 3 on the phone over the course of 2 weeks, and 8 onsite (two via skype) over the course of a day.
The questions were very behavioural and were more geared towards whether or not I was a fit for the culture. In that respect, the interview process was not difficult, but it was a whole day of constant interviewing. Even lunch was (a more casual, but still) an interview. That being said, the interview process was a glimpse of the exciting world of a Rioter - where they work and play hard.
All in all, I wish that I could have had the experience to work at this terrific company, but the compensation was lacking and I wasn't ready to back down.