Casey Winter is the default character in the spin-off mystery investigation game The X-Files: Deep State. At the beginning of the game, she is a rookie FBI agent with a background in criminal psychology.
The player can choose gender, race, name and physical appearance of the main character, as well as affect their personality through dialogue choices. Both male and female versions of the agent are called Casey Winter by default, although the player can change their name at any point.
The choices players make along the way award Winter with points of reputation, which scales from Believer to Sceptic, and ideology, which scales from Xenocentric to Humanist. These attributes, as well as other choices Winter makes, affect how other characters perceive her, the outcome of certain events, and access to special in-game content.
Although big parts of Winter's biography are left to the player's imagination, some details can be pieced together from dialogue and game events.
During a conversation with Garret Dale in Chapter #2 of the game, Winter mentions that she grew up in a small rural town called Delta Glen. Depending on the player's choice, her father was either a sheriff, a farmer, a butcher, or a preacher.
In the same conversation, she tells Dale that her decision to join the FBI was inspired by two agents who stopped a spree killer in the town when she was little.
It is worth to say that Delta Glen is the fictional town from the Red Museum episode of the show. As such, the two agents who inspired little Winter to join the FBI are most likely Mulder and Scully, and the killer she talks about is the Crew Cut Man.
Rookie FBI agent
Faithful to her dream, Winter eventually became an agent in the Violent Crimes Section of the FBI. At the beginning of the game, which takes place in the spring of 2010, she is a rookie partnered up with a more experienced agent, Garret Dale. Together they are sent to investigate the murder of District Attorney Karen Cooper (Prologue: The Monster). Despite the confession of Mark Cooper, victim's husband, Winter starts to suspect that their son, Davey, inadvertently killed his abusive mother with psychic abilities. When Mark Cooper begs her to keep that suspicion to herself, she can either allow him to take the fall or arrest Davey.
Their next case involves a schizophrenic physicist, Dr. Gordon Dillahunt - Winter's former professor (Case #1: Trust no 1). Dillahunt is accused of a gruesome double murder, but maintains his innocence. Following the clues, Winter and Dale not only prove his innocence, but also uncover a plot to assassinate the president. After an altercation in the White House, during which Winter shoots a green blood hybrid, she is arrested and interrogated by Jane Doe. Winter is subsequently released and ordered to surrender Dillahunt to authorities. She can either comply or help Dillahunt escape.
The X-Files Unit
Following the Dillahunt Case, Winter and Dale are transferred to the newly reopened X-Files unit. Their first case concerns a series of gruesome deaths in Lexington, Kentucky (Case #2: In Corpore Sano). With the help of medical examiner Dr. Maria Rivera they discover that these deaths were caused by a deadly virus that causes spontaneous mutations of the body. Winter traces the virus to its origin - a clandestine medical research funded by the Department of Homeland Security. To stop the virus from spreading, she has to find the patient zero, Henry Malone. Winter confronts Malone in the airport and has to either shoot him dead or give him to Jane Doe, who is working for the DHS, with the implication that he'll be used to create a horrible biological weapon.
During the Leper King investigation (Case #3: The Leper King), Winter and Dale are sent to assist Dale's uncle, a prominent senator, who is being blackmailed by a hacker nicknamed the King. They track the hacker to its lair and, before it is destroyed, manage to download sensitive files. From these files, they learn about the Syndicate and Senator Dale's ties to it. The hacker is after an illegal medical database that had been compiled prior to the Syndicate's destruction, and the senator knows where to find it. Depending on Winter's choices, the King gets either the full database or only a fragment of it. Senator Dale is placed in protective custody, but hangs himself shortly after.
Sometime later Winter, Dale and Dr. Rivera go to a desert art festival called the Blazing Man (Case #4: Light from Above), where someone was killed by what witnesses are describing as a landing flying saucer. Winter gets dozed with psychedelic drugs and spends the night talking to dogs and harassing bystanders. Eventually she comes to her senses and solves the murder, which, as it turns out, had nothing to do with aliens. Instead, it was an art performance sabotaged by the murderer, or the murderers, depending on whom Winter decides to accuse.
Winter and Dale are present during the particle accelerator explosion at the Horizon Lab, and get stuck in the underground laboratory with five scientists until the automatic 72 hour-long lockdown is lifted (Case #5: Devil ex Machina). After one of the scientists mysteriously dies, the survivors begin to suspect that something evil was pulled into our world by the explosion, and is now hiding inside one of them. Winter and Dale get trapped inside a test chamber and exposed to a potentially lethal dose of radiation, but manage to escape and destroy the creature. However, mere seconds before the lockdown is lifted Winter starts to suspect that the last surviving scientist, Emily Barrow, is possessed. She can either shoot her or risk the creature escaping the laboratory.
With Dale slowly dying of radiation poisoning, Winter gets blamed for the death of the scientists and suspended (Case #6: Water Gate). Desperate to save her partner, she goes to an abandoned Syndicate laboratory. There she finds Dr. Gordon Dillahunt, who is being kept captive by a sinister shadow organization known as the Resistance. There's another captive in the laboratory - an alien Alien Bounty Hunter. His spinal fluid, called "Substance X" by the Resistance, can save Dale, but before Winter can escape with it, Jane Doe appears and points a gun at her. Jane Doe tells Winter that the true goal of the Resistance is to stop the approaching alien invasion, at any cost necessary, and that it was formed by the surviving hybrids after the Syndicate was destroyed. She is then attacked by the Bounty Hunter, which triggers the self-destruct protocol of the laboratory. Dr. Dillahunt sacrifices himself to let Winter escape, and she in turn can try to help Jane Doe survive or leave her to die. In any case, Winter is wounded during the escape and comes to in the Our Lady of Sorrows hospital, where she is being treated by Dana Scully. Winter asks Scully to inject Dale with Substance X, which saves his life.
- If the player changes the main character's name to Fox Mulder or Dana Scully, characters in the game will be surprised and comment on that.
- In Chapter #5 it is revealed that Winter's older brother, Brandon, was one of the teenagers killed by the Crew Cut Man. This fact strongly suggests that he was inoculated with alien DNA as a part of the "Purity Control" program.
- In Chapter #6 Jane Doe tries to convince Winter that she, too, was injected with alien DNA as a child. It is unclear if Jane Doe is telling the truth, however the evidence suggests that she does: in particular, Winter's immunity to the toxic effect of Francis Stover's green blood. If true, it would explain why she was unaffected by Henry Malone's virus, resistant to radiation during the Horizon Lab incident, and how she survived the drone strike during the Leper King investigation.