What are the best single player & open world survival-horror games on the PC with a focus on base building?
The open world survival horror genre is one that has only recently gained popularity with the advent of the Arma 2 mod, DayZ. Being such a new genre, many of the titles are still in early development, something else that is also a recent trend in PC gaming.
Generally an open world survival horror game consists of the player searching and scavenging a post apocalyptic like environment for tools, weapons, and building materials that can then be crafted into some form of shelter or base. This base is then used as a storage place for more of the players found equipment that can be stockpiled and used for further survival. Oftentimes these games also feature permadeath, in that if the player dies they have to start all over again from scratch.