A free program for Windows, by Nvidia.

Vault 1080 is a first-person survival horror mod that leads you through a foggy, murky marsh to the ruins of an old church. Bright shafts of light guide you through the shadows to the vault, which contains three large levels of buried secrets and hidden horrors.

This is the story of a misguided congregation that embraced darkness and sickness in order to survive. The objective of the game is to uncover the story of the church and its past. You will have to find out what happened and why the people in the church are acting in such a strange way.