Besides Alien: Isolation, horror games usually aren't very long games. The most interesting upcoming game in the genre is currently The Callisto Protocol, and that game will seemingly be quite a bit lot longer than the average horror adventure.
In the latest issue of Edge Magazine (via Shinobi602 on Twitter), it is revealed that a playthrough will probably take you 12-14 hours. There will also be different paths to choose from to add replayability, and it seems like there might actually be quite the few of those as the developers say "We don't tell you where they are or how many they are".
Let's just says this didn't exactly lessen our expectations on The Callisto Protocol, which launches for PC, PlayStation 5 and Xbox Series S/X on December 22.