1st - Interview with HR, basic questions about you experience/studies and a general explanation of how Rockstar works, which will be your responsibilities and how the recruiting process will be.
2nd - A codility test with 3 questions about string manipulation, BFS, graphs... the typical, which a 2 hour deadline. Quite doable in the timeframe they provide, a really positive test experience.
Based on what the recruited said in the first interview, the next stages would've been another meeting with the head of the GPP team to further discuss responsibilities and candidate knowledge to see if it is a correct fit and after that, an in-place interview in Edinburgh (with paid expenses) where they'll show the candidate studio itself and practically propose and seal the job offer. Sadly, I was discarded after the second stage, so these last two stages should be taken with a grain of salt because they are only based in what the HR explained in the first interview, and there could be some modifications or changes with them.
It was a pretty comfortable recruiting process, and the recruiter stayed in touch during the whole duration of it.