To say the least, finding the right length for a game can be difficult, especially because the ideal length can differ greatly depending on what genre the game belongs to. This applies equally to Frictional Games' upcoming Amnesia: The Bunker.
Frederik Olsson, Amnesia: The Bunker's creative director, said that a horror game would take roughly 4-6 hours on average, although he noted that it depends on the players' decisions as well as other factors such as dynamic and random nature of the game and the player's ability.
The Dark Descent and Rebirth both had semi-open world designs and more dynamic and randomized gameplay elements like in The Bunker.
Amnesia: The Bunker is available now on Xbox Series X/S, Xbox One, PS4, and PC, and will be released on May 16th.