Arx Fatalis is a first-person dungeon-crawling action-RPG from 2002 by Arkane Studios, the team who would later go on to develop Dark Messiah of Might and Magic in 2006 and Dishonored in 2012. Inspired by the Ultima Underworld games from the early 90s, Arx Fatalis is a modern adaptation of old school design. The world of Arx Fatalis is set entirely underground, after a dying sun forces humans, goblins, and trolls to retreat to the old dwarven mines and rebuild their cities underground. You play a nameless human who wakes up in a goblin prison cell with no memory of his past or his own identity. While attempting to recover your lost memories, you learn that you were sent to Arx to prevent an evil god from awakening, which becomes your main quest for the remainder of the game.
Like Arkane's other games, the draw in Arx Fatalis is that it offers players a lot of freedom to decide how to play the game, in terms of building your character in an open class system, how you choose to approach situations and solve puzzles, and how you go about exploring the world. This isn't a thorough, in-depth RPG with dialogue options and multiple solutions to quests, or an open-world sandbox game that lets you go wherever you want and do whatever you want, but it takes elements from those types of games and implements them in a more streamlined fashion. Normally, I would consider streamlining a very bad thing in an RPG, but the execution in Arx Fatalis offers plenty of satisfying depth while keeping the game's pace moving forward in a meaningful direction.