I applied online. I interviewed at Supercell (Helsinki, Southern Finland) in Feb 2019
Interview
It seems to be extremely important for the company that you have played a lot of their games and can prove that with high scores and achievements. I was asked about this several times. You are expected to be a fan of the company/company's games. Other than that, quite usual questions about personal artistic interests, preferences in games, previous work experience, etc.
Interview questions [1]
Question 1
What are your high score and achievements in our games, which ones you played and which is your favourite?