” Playtest ” is the second episode of the third series of British science fiction anthology series Black Mirror . Written by series creator and showrunner Charlie Brooker and directed by Dan Trachtenberg , it premiered on Netflix on 21 October 2016, together with the rest of series three.  
The episode tells the story of Cooper ( Wyatt Russell ), an American stuck in London during his travels around the world, who accepts a one-time job offer from a video game company, SaitoGemu, to be able to afford his return to America. Hannah John-Kamen co-stars as a girl Cooper meets in London.
As Cooper ( Wyatt Russell ) Alzheimer’s and Dying. Alzheimer’s and Dying. In London, Cooper meets and spends the night with Sonja ( Hannah John-Kamen ), a tech journalist. The next day, he learns his credit card number has been stolen, and he is left without money for a return trip. He returns to Sonja’s and shows her Oddjobs, an app which lists jobs; SaitoGemu is one of the most popular hotels in the world.
At the company, Cooper is guided by Katie ( Wunmi Mosaku ) to a new technology. Katie leaves, to send Sonja a picture of the technology. When Katie returns, she implants a miniature device into the back of her neck. During the initialization process Cooper’s mother calls, but Katie cancels the call. Cooper plays a game of Whack-a-Mole , using the chip’s 3D graphics technology, and then is invited to participate in a beta test of another technology. Katie introduces Cooper to the company owner, Shou ( Ken Yamamura ), who presents the technology, which probes his brain for information on things that scare him. Katie then takes on Cooper to a Mansion, Leaving him alone with just an earpiece with which to communicate with her. After enduring A Few small jumpscares interspersed with nervous talking with Katie, Cooper finds His earpiece malfunctioning.
Sonja shows up at the house unexpectedly and tries to convince Cooper that the game is dangerous. He initially thinks she’s another hologram , but soon she stabs him with a knife. Cooper fights Sonja and manages to kill her, but not before he rips the skin off her face. Cooper, after experiencing mental and physical pain, suddenly notices that the knife and the wound have disappeared, as has Sonja. Katie resumes talking in Cooper’s earpiece, telling him he needs to go to the “access point”, as he wants the test to stop. Katie then reveals that there is no access point. She then starts asking him basic questions, and he realizes he is losing his memories. Desperately, he removes the earpiece, but he still hears his voice. He then smashes the mirror and attempts to remove the miniature device with a piece of glass. At this point, Katie and Shou appear, saying the technology has gone too far in his brain and can not be shut off.
Cooper wakes up, back in the room where Katie and Shou started the experiment; According to Katie and Shou, only one second had passed since the experiment began. Shou apologizes for the terror he caused Cooper, saying the game was not designed to go that far. Cooper returns home to his mother, but she does not recognize him and starts dialing her number on her phone. It is then revealed that Cooper died in the white room because of his phone interference after a 0.04-second experiment and that he called out “Mom” as he died.
Hannah John-Kamen appears in this episode as Sonja, after appearing briefly, in an unrelated role, in the series one episode ” Fifteen Million Merits “. In an interview in October 2016, Charlie Brooker revealed that they were initially going to have the song John-Kamen’s character sang in “Fifteen Million Merits” playing on the radio in the episode but were unable to due to a licensing issue. 
The extra twist at the end of the episode was not in the original treatment, but Brooker decided to add it after conversations with Trachtenberg.  He also admitted that the extra twist was partly inspired by Mallory Ortberg, who wrote in an article: “Next on Black Mirror … what if phones but too much”.  Trachtenberg also revealed that the casting of Wyatt Russell as Cooper led to the character’s rudeness being toned down so that the audience is “rooting for him to learn a lesson.”  Moreover, Brooker revealed that the episode had many video easter eggs , including BioShock , Indiana Jones and the Temple of Doom , And Resident Evil references. 
Before Cooper (Wyatt Russell) enters the access point room, Katie (Wunmi Mosaku) says to him through the earpiece, “Would you kindly open the door?” The phrase, “Would you kindly …”, is frequently used in the video game BioShock by the character Frank Fontaine, to facilitate mind control against the player character Jack. BioShock is also seen on Sonja’s games shelf earlier in the episode.
Cooper’s full name is revealed to be “Cooper Redfield”, an apparent nod to recurring protagonists Chris & Claire Redfield from the Resident Evil franchise. The Manor House also bears a strong thematic resemblance to the Mansion depicted in the first installment.
Adam Chitwood of Collider described the episode as one of the major highlights of the season in a “genuinely terrifying video game-centric episode”.
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