Plot: Afraid of Monsters: Director's Cut is a mod for Half-Life developed by Team Psykskallar, known for its infamous horror aspects. It is a major update of the mod Afraid of Monsters.
Plot: They Hunger is a single player horror mod for Half-Life developed by Black Widow Games. It is divided into three chapters, which were distributed on the internet over a span of three years. Current distributions of the game include all three chapters.
Plot: Half-Life: Echoes is a game modification of Half-Life created by British developer James MrGnang Coburn, released on August 10, 2018. The mod was under development for four years and uses the GoldSrc engine. Wikipedia
Plot: Gunman Chronicles or Half-Life: Gunman is a first-person shooter space western video game originally created as a mod by the now defunct Rewolf Software. Gunman Chronicles was originally a Quake deathmatch mod named Gunmanship 101, then it was moved to Quake II's engine before becoming a Half-Life...
Plot: Half-Life: Blue Shift is an expansion pack for the first-person shooter video game Half-Life. It was developed by Gearbox Software with Valve and published by Sierra On-Line. Blue Shift was the second expansion for Half-Life, originally intended as part of a Dreamcast port of Half-Life. Wikipedia