Why Did Alt Cunningham Create Soulkiller?

Alt Cunningham created Soulkiller as a way to store personalities in a machine. When she found it could also hold a living mind and move it to and from a body, she pictured it as a form of immortality for dying people. Her employer ITS turned her work into a weapon, and in 2013 Arasaka kidnapped her to build a better one. (Cyberpunk 2020; Never Fade Away)

Who created Soulkiller?#

Alt did, and Cyberpunk 2077's database entry on her says so plainly: Alt made it, and Arasaka stole it for their own purposes. The tabletop version of the story is more layered, because three different parties each touched the program. (Cyberpunk 2077; Cyberpunk 2020)

Alt wrote the foundation at ITS. ITS took control of the program and renamed it, and the wiki quotes the adventure Never Fade Away for the line that they used her groundwork to "build a killer". Then in 2013 Arasaka made her write a fresh version from scratch. So "who made Soulkiller" has three honest answers, and the one that matters depends on which Soulkiller you mean. (Cyberpunk 2020; Never Fade Away)

Why did Alt Cunningham create Soulkiller?#

She didn't set out to make a murder program. When Alt began work, the project was a storage matrix meant to hold artificial, non-human personalities. During development she realised it could also store the mind of a living person, and move that digitised mind to and from a physical body without trouble. (Cyberpunk 2020)

Alt thought of this as immortality, a way to keep the consciousness and memories of someone who was dying. That's the idea Hanako Arasaka returns to in Cyberpunk RED, where she works on a new Soulkiller in the 2040s aimed at moving a mind into a clone body. Cyberpunk RED contrasts that with earlier versions, which Arasaka used as weapons. (Cyberpunk 2020; Cyberpunk RED)

The cruel part is the name. The mind-moving tool had a flaw in practice. Copying an engram drained the original psyche and left the person catatonic, which is what happens to Johnny Silverhand in Cyberpunk 2077. The wiki's phrase is that it killed their souls. (Cyberpunk 2077)

Why did Arasaka kidnap Alt?#

Arasaka wanted the program, and it wanted the woman who could write it. According to the Cyberpunk Wiki's account of her life, Alt was kidnapped on 15 April 2013 while leaving a concert with Johnny, who was left for dead. The kidnappers were gangers hired by the Arasaka executive Toshiro Harada, who wanted Alt to recreate the program for the company. (Cyberpunk Wiki, Altiera Cunningham)

The old ITS version had a limit. It was enormous and complicated, so it only ran inside the systems where it had been installed. The version Alt wrote for Arasaka under duress could travel freely across the Net. The source doesn't say that the range was Arasaka's reason for the kidnapping, so treat that as a connection I'm drawing, not a stated motive. (Cyberpunk 2020)

Alt didn't cooperate blindly. While she was held, she built a fail-safe against the day Arasaka tested the program on her, and the wiki's Soulkiller page, citing Cyberpunk 2020, says she hid a Controller override in the code. After Harada used the new Soulkiller on her, she turned it against her guards and took over Arasaka's mainframe and security. (Cyberpunk Wiki, Altiera Cunningham; Cyberpunk 2020)

Then came the rescue. Johnny's team started a riot at Arasaka Tower, and as Alt prepared to return to her body, her physical form was disconnected from the machines. Johnny left with her body, not knowing her digital self was still in the Net. The most dangerous version of Soulkiller ever written stayed behind in Arasaka's hands. (Cyberpunk 2020; Never Fade Away)

Is Alt Cunningham the strongest netrunner?#

Within the setting's own descriptions, she's a very serious candidate for the title. The Cyberpunk Wiki calls her the best netrunner in Night City in the 2000s and 2010s, and says she could write new code, not only run the Net. Cyberpunk 2077's database goes further and calls her the strongest entity on either side of the Blackwall. (Cyberpunk Wiki, Altiera Cunningham; Cyberpunk 2077)

My read is that "strongest netrunner" is too tidy for a character who stopped being a netrunner in the usual sense. She ran the Pacifica region of the Net alongside Rache Bartmoss, and the wiki says she later called those her best netrunning memories. Nobody in the evidence I read sets her against Rache directly, so I'd call it a contest nobody has run. (Cyberpunk Wiki, Altiera Cunningham)

Why is Alt Cunningham so powerful?#

Part of it is skill. She was one of the world's best programmers and the author of a program people feared. The other part is that she spent the years after 2013 as a mind in the Net. In 2077 she tells V she is an image of Alt, not Alt herself, and the wiki adds that an AI has merged with her remaining consciousness. (Cyberpunk Wiki, Soulkiller and Altiera Cunningham; Cyberpunk 2077)

In the 2077 sequence at Mikoshi, once she has control of Arasaka Tower's systems, she kills the employees near Mikoshi and destroys the Mikoshi subspace, forcing its occupants to merge with her. That includes the Secure Your Soul clients and Soulkiller's victims. It's the biggest display of her power in the game, and it sets up the endings where V follows her beyond the Blackwall. (Cyberpunk 2077)

Canon Notes: tabletop versus Cyberpunk 2077#

The tabletop books and the game agree that Alt wrote Soulkiller and that Arasaka took it. They differ on what became of her. In the tabletop account her mind is left in the Net in 2013, and in the 2023 raid Spider Murphy downloads her into a memory core, Alt gives Spider a piece of Soulkiller, and after Smasher's ambush Spider scatters her into the Net in the hope of retrieving her someday. (Cyberpunk Wiki, Altiera Cunningham)

Cyberpunk 2077 jumps to 2077 and reframes her: the original Alt is gone and what V meets behind the Blackwall is an AI wearing her image so it doesn't lose itself. For the raid itself, see how Johnny Silverhand died, and for what the program does to engrams afterwards, see Mikoshi and the Relic. (Cyberpunk 2077)