The Legacy: Realm of Terror is described as 'The year is 1993. The protagonist's ancestors, the Winthrops, have obviously dealt with black magic and perhaps even pacts with the demons' and is a Horror Game in the Games category. There are more than 10 games similar to The Legacy: Realm of Terror for a variety of platforms, including Windows, Mac, Linux, Steam and Playstation. The best alternative is Left 4 Dead. It's not free, so if you're looking for a free alternative, you could try SCP: Containment Breach or Cry of Fear. Other The Legacy: Realm of Terror like games are Amnesia: The Dark Descent (Paid), Resident Evil (Paid), Dying Light (Paid) and Dead Island (Paid).
Amnesia: The Dark Descent is a first person survival horror game for Windows, Mac OS X and Linux. The game features a protagonist named Daniel exploring a dark and foreboding castle, while avoiding monsters and other obstructions as well as solving puzzles.
Resident Evil, known as Biohazard in Japan, is a survival horror video game-based media franchise created by Shinji Mikami and Tokuro Fujiwara and owned by the video game company Capcom. Represent entire series of Resident Evil games.
Dying Light is an open world first person action-adventure survival horror video game developed by Polish video game developer Techland and published by Warner Bros. Represent entire series of Dying Light games.
Dead Island features an apparent open world roaming, divided by relatively large areas, and played from a first-person perspective. Most of the gameplay is built around combat and completing quests. Represent entire series of Dead Island games.
Slender: The Eight Pages is a free indie-developed psychological horror/survival horror video game for Microsoft Windows and OS X. The game is based on the Something Awful forums' creation, Slender Man.
SCP: Containment Breach is an indie survival horror video game based on the stories of the SCP Foundation website. The player guides a test subject, D-9341, through many obstacles inside of a facility belonging to the shadowy SCP Foundation.
Layers of Fear is an foray into madness, a first-person horror game that sets a tone of fear and dread through provocative story telling as you explore a Victorian setting complete with mood-setting art pieces.