Amnesia: The Dark Descent

On 19 August 1839, a young man awakens in the dark and empty halls of Brennenburg Castle in Prussia with no memory about himself or his past. All he can remember is that his name is Daniel, that he lives in Mayfair, and that someone or something is hunting him. Shortly after regaining consciousness, Daniel finds a note he wrote to himself, which informs him that he has deliberately erased his own memory and is being hunted by a "Shadow", an unearthly presence that manifests itself through fleshy, acidic growths spreading throughout the castle. The note instructs Daniel to descend into the Inner Sanctum of the castle in order to find and kill its baron, Alexander.
As he makes his way through the castle, Daniel gradually learns both about its mysteries and about his own past, through notes and diaries he finds as well as through sudden flashbacks and visions. The origin of his situation is a mysterious orb that he recovered from the Tin Hinan Tomb in Algeria. When the orb was shattered, Daniel received a vision which enabled him to reassemble it, unleashing the Shadow in the process. Each of the experts he consulted in person about the orb were later found gruesomely dismembered. Disturbed by this, Daniel desperately exhausted all archaeological leads into strange orbs until contacted by Alexander, who summoned him to Brennenburg. There, Alexander informed him that the Shadow was slowly stalking him, killing everyone he came into contact with, and will not stop until it kills him as well. Alexander promised a means of repelling the Shadow by ritualistically coating the orb with a "vitae" substance, which could only be harvested from humans experiencing extreme pain and agony. Alexander's true purpose is to use Daniel's vitae-enriched orb to return to his native dimension, from which he was banished centuries prior. To achieve this end, Alexander and Daniel gathered vitae by torturing prisoners in the castle dungeons, many of whom were innocent people that Alexander claimed to be murderous criminals.
To maximize the production of vitae, the victims were forced to consume a potion that induced amnesia, so that they could never grow accustomed to their torment. Daniel slowly realized that the rituals were becoming less effective and the Shadow was getting ever closer. Desperate to survive, he became sadistic in his attempts to harvest vitae, and accidentally killed two escaping prisoners, a mother and her young daughter, in a fit of rage. Following the final ritual, Alexander sensed Daniel's guilt and declining faith in him and left him for dead as a result. Realizing how Alexander had manipulated him, Daniel swore revenge and consumed an amnesia potion in order to overcome his paralyzing guilt.
As Daniel nears the Inner Sanctum, he encounters Heinrich Cornelius Agrippa, a man who had once studied the orbs with his student Johann Weyer and has since been kept alive and imprisoned by Alexander, due to his extensive knowledge on the subject and as leverage against Weyer. He tells Daniel that Weyer stole Alexander's previous orb and harnessed its power to travel between dimensions. When Daniel asserts that he has learned to reassemble orbs, Agrippa instructs him to find his own shattered orb, which is needed to breach the Inner Sanctum. Agrippa also asks Daniel to take with him his head, which can be severed alive using a tonic invented by Weyer, and throw it into the inter-dimensional portal after Alexander opens it.
Once Daniel enters the Inner Sanctum, he finds Alexander preparing to open the portal. From here, there are three possible endings:

If the player does nothing, Alexander enters the portal, leaving Daniel to be killed by the Shadow and descends into darkness, while Alexander tells him his sacrifice will be forever celebrated.
If the player prevents the portal from opening by knocking over its support columns, the Shadow kills Alexander and spares Daniel, allowing him to leave the castle, content with his redemption.
If the player throws Agrippa's head into the portal, the Shadow kills both Alexander and Daniel. In the darkness, Agrippa assures Daniel that everything will be alright, calling upon Weyer to help him.
A secret fourth ending, similar to the one where Alexander escapes, can be obtained at an earlier point when Daniel is captured and imprisoned by Gatherers. If the player waits in the prison cell for an extended period of time, the Shadow will arrive and kill Daniel, with Alexander once more thanking him for his sacrifice.

Amnesia: Justine

The player takes control of an unnamed woman, who awakens with amnesia in a dungeon cell. A phonograph in the cell contains a recording by a woman named Justine, who tells the unnamed woman that she is the subject of a psychological test. The woman must overcome three puzzles to escape the dungeon. In each, she has the option of simply abandoning the puzzle and walking away, but doing so will cause an innocent victim to die. She is also pursued by the Suitors, three monstrous characters who turn out to be Justine's former paramours, now twisted by physical and psychological torture. After surviving the puzzle sections, the woman discovers a phonograph dangling from the ceiling, which causes the walls of the chamber to close in and threaten to crush the woman. She passes out, but awakens unharmed and begins to congratulate herself, revealing that the woman is Justine herself, who staged the entire experiment to see if she still had any compassion for humanity within herself. The ending sequence's dialogue differs depending on the number of people Justine had rescued.