Judging by Riot's job ads and glassdoor notes, playing LoL is required to get a job there. From what I know there is no gameplay in this game other than competition.
We do hire people who don't play League of Legends, though we are looking for people who are passionate about games LoL or others.
That's good to know. The job ads imply otherwise (I posted a quote elsewhere in these comments, and this is the new language, I remember it was saying effectively "must be an LoL player" few years ago). Not sure if you care, but I am not the only one who gets this impression and excludes Riot from the job search.
Thanks for the feedback, I'll let the recruiters know.