Tell the genre of the game "Resident Evil: Revelations".
genre refers to genre_name; game "Resident Evil: Revelations" refers to game_name = 'Resident Evil: Revelations'
SELECT T2.genre_name FROM game AS T1 INNER JOIN genre AS T2 ON T1.genre_id = T2.id WHERE T1.game_name = 'Resident Evil: Revelations'