What is genre of Arx Fatalis?

There is a FAQ right at the top of this forum. It says this:

What is this Arx Fatalis?
Arx Fatalis ("fatal fortress") is a single player RPG and action adventure set underground on a world whose star has failed. The various races have been forced underground (Goblins, Trolls, Ratmen, Humans, etc.) to cope with sub-freezing temperatures of the surface. But alas, something is rotten in the fatal fortress... An evil cult plots to manifest the evil Akbaa and destroy Humanity, and it is your job to stop it.