Miasmata is described as 'You play as Robert Hughes, a plague-stricken scientist on a journey to discover a cure. Your adventure begins on the shores of a remote island called Eden. Long ago, Eden was inhabited by a group of indigenous people, whose extant monuments still decorate the island landscape'. There are more than 10 games similar to Miasmata for a variety of platforms, including Windows, Mac, Steam, Linux and Playstation. The best alternative is Amnesia: The Dark Descent. It's not free, so if you're looking for a free alternative, you could try Cry of Fear or SCP: Containment Breach. Other Miasmata like games are Slender: The Eight Pages (Paid), Alien: Isolation (Paid), Layers of Fear (Paid) and SOMA (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.
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.
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.
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.
Penumbra: Overture is the first in a series of episodic survival horror games developed by Swedish developer Frictional Games. It was originally intended as the first episode of a trilogy. Represent entire series of Penumbra games.