This is a Garry's Mod gamemode I developed as an experiment to see how much of a horror atmosphere I could introduce to an existing level using dynamically generated audio & visual effects. Everyone loved how it turned out and asked me to add more of a "game" to it; which I eventually did. There are several puzzle-quests the player(s) are put through.

YouTube Video: https://www.youtube.com/watch?v=FwC-3Ubap9c