If you can pass the the phone screen, here's how your interviewing day will go. If you are flying in from out of town, they'll put you up at either the Best Western or the Hotel Ambrose, which are hotels within 4 - 5 blocks (walking distance) of the Riot Games building.
Speaking of the Riot Games building, it's a nondescript office building with about four / five floors in a complex with other companies. The office environment are "pods", where teams are in non-existent cubicle spaces (the only "walls" per se are the monitors from the screens in front of you as an employee). Some of the floors are darker (where some or all of the overhead lights are turned off), some parts of the office the florescent lights are all on.
While you're doing your interview day, you'll be working with a recruiting coordinator who set up your interviews and sometimes moves you from meeting room to meeting room. I wasn't given the schedule beforehand or during my day at Riot, although everybody I spoke with had a copy in front of them.
Some of the folks I talked to were on a team in St. Louis (which is where Riot Games has a smaller office, probably a quarter of the size of the Santa Monica office). Their video conference room wasn't an idea setup for an interview though, since both myself and the other guys were far away from the camera and I couldn't see them up close or very well.
During the time on site, I wasn't asked any technical questions that I thought were out of line. I'm copying one that I remember below, which is actually a relatively standard question which many coders see in technical interviews at other companies. I believe the bigger technical challenges were posed to me during the phone portions of the interview process.
Being on site was basically a "is this candidate a suitable chump to work with our team" set of meetings. And this is where I spectacularly failed the process. After a seemingly cordial lunch meeting with the hiring manager where I was subsequently deposited in a meeting room and sat alone for about 10 minutes, the H.R. person (who is not the same person as the recruiting coordinator who sets up your travel and gets you into the meeting room) came out to me, introduced himself, and then ejected me out of the interview process a number of hours early. This was the first time it's happened in my years of interviewing and it was exceptionally humiliating, but I am guessing my personality or simply the approach I was taking with my potential co-workers really rubbed them the wrong way. As I was being escorted out the door, the interview / recruiting coordinator was quite apologetic and in retrospect, truly the nicest person I met in the process, but I was still very hurt & sore the entire ride back to my home city. And of course I got absolutely no useful or constructive post-interview feedback from Riot Games or my headhunter.
But hopefully my experience flunking the interview will mentally prep you for what to expect for your interview day. If you find my notes helpful, please let me know by voting "yes" on the "Helpful?" link above.