They have a fairly typical process for tech companies:

• Initial phone screen
• Technical phone screen
• On-site full day of interviews

They screen for both job-related background and gaming experience (and specific experience with LoL), and seem to value both fairly equally in the selection process. This means you're not going to get an offer there unless you are highly passionate about both.

I'm not going to get into specifics of questions, out of respect for their process. However, I did find it somewhat odd that the on-site interviews focused almost exclusively on inter-personal interactions and inter-department communication, and not at all on technical topics.

They also have somewhat conflicting information about what type of people they are looking for. For example, public materials tout being bold and passionate, but feedback from the interview process emphasized the need for people who are cautious, diplomatic, and work well inside a larger organization.

I also thought it was odd that they would pull people with smaller company backgrounds and experiences into their process when that seemed to be an automatic disqualification factor based on the post-interview feedback.

I have to give them credit for communicating why they are not extending an offer, though; not enough companies do this.

I feel like they are still working out how to get everyone on the same page for what they are looking for as they grow and update their "smaller company" materials and messaging to match their new "bigger company" mentality.

I think the people there handled the process very nicely and professionally, though, aside from some issues with effectively communicating the qualities they were actually looking for.

Without getting into specifics, there's a focus on gaming, your LoL gameplay experience, Riot's public company materials, and company processes inside a larger organization.