Anyone who’s been online in the last month has likely heard of the new Elden Ring expansion Shadow of the Erdtree. The first and only major update to one of the best RPGs of the last decade has caused a stir not just for being incredible to play, but for its crushing difficulty that’s left even seasoned veterans of the “soulslike” genre reeling.
But for some, the extreme challenges of FromSoftware’s latest release aren’t enough, leading to impressive feats of ingenuity as creators find new ways to make the famously hard game even harder. One such player is U.K.-based YouTuber and Twitch streamer perrikaryal, whose attempt to complete the DLC entirely hands-free has given new meaning to the term mind game.
While many are currently struggling to beat Shadow of the Erdtree’s many grueling boss fights with just a standard controller, the streamer, who goes by Perri on her socials and asked Rolling Stone to withhold her real name for her privacy, has opted to tackle the game using so-called “mind control” — that is, programming devices that recognize both brain activity and eye movements to control her game play. In doing so, she hopes to showcase methods of broadening the scope of hands-free game design to become more accessible in the future.
Perri’s setup begins with a headset that measures the electrical activity in her brain, known as an electroencephalogram (EEG for short). The specific device she uses is made by Emotiv, a bioinformatics company that specializes in EEG devices and BCI (brain-computer interface) software. EEGs are traditionally used to diagnose epilepsy, and they can read brain activity to determine how patients’ minds are perceiving stimuli.
“In terms of psychological research, it’s good for seeing if someone has a reaction to something,” Perri explains. “So, if you smack someone across the face, for example, you can see what happens [and] when.”
For gaming, Perri attaches 14 electrodes to her scalp that read her brain’s reaction to specific thoughts to initiate cognitive activity, as well a pair of EEG earbuds that register pulsing of her ear muscles to get a more direct physical response for certain actions. They’re then combined with a separate eye-tracking camera, which uses her eye and head movement to simulate mouse or joystick positioning. Through a mix of Emotiv’s BCI software and her own “janky” coding, Perri assigns individual in-game abilities to specific thoughts so she can use subtle motion to lead her character and manage the in-game camera, while imagining doing actions like spinning a plate or moving a block perform the more complex actions.
“I have two different profiles,” she says. “One for boss fights, and then one for scampering through the environment. It’s pushing a cube to dodge, spinning a plate to [use a skill]. I’ll imagine a little cricket jumping while I pulse my inner ear muscles so that one’s a little bit hacky, but that’s what it is when I want to attack.”
It took a lot of trial and error for Perri to get this far. The streamer first encountered EEG machines while studying psychology at university and was blown away. Consumer-friendly versions of the headsets aren’t cheap, but the version she uses is readily available online, and vastly less expensive than what you’d see in a lab or hospital.
Chronicling her experiments over streams and YouTube videos, Perri’s story took off in earnest when she pivoted her attention to Elden Ring, a game she hadn’t even played the normal way.
Of course, this all required a massive learning curve. Of all the actions she has to routinely balance, healing her character is one of the most difficult, as Perri must think about becoming agitated or tense to regain health. As she quickly discovered, mimicking anger can easily be misread as the actual frustration of repeatedly playing a super hard game. If Perri allows herself to become genuinely frustrated, her headset will pick it up as a call to heal. But to maintain command in Elden Ring, it’s essential to retain total control.
“You have to calm down. It’s like mindfulness,” she says. “I’m meditating the entire time and when I’m imagining, it’s not being tense, it’s imagining being tense.”
Mimicking tension without succumbing to it is a challenge in its own right, but the game itself frequently throws wrenches in the mix by its design. When asked which of the game’s boss encounters were the hardest to beat, she looks back to the Elden Ring base game that she beat in 2023, where she repeatedly failed to beat an otherwise medium-difficulty foe because of a particularly challenging element: The fight features a camera perpetually rotating around the combat plane, which triggered the spinning plate imagery in her head, leading to Perri consistently using the wrong inputs and leaving her disoriented.
Since that 2023 run, Perri’s made some upgrades to her setup. Initially, she needed a controller to handle movement, but with the addition of eye tracking and gyroscopic sensors to the kit, as well as the in-ear buds to measure her muscle tension, she’s now able to fully control everything, hands-free. But it may be pure luck that Elden Ring is viable for this play method, other games certainly aren’t.
During a month-long marathon of trying different games, Perri started running into issues with menu navigation. She could play online titles like Valorant, which feature streamlined modes that require little fiddling with selections, but something like Counter-Strike was too much because of the in-game purchases required at the start of every round. The hardest game to play, however, was Tetris — a notoriously easy game to play that, using her setup, became unplayably hard. “When I’m playing Tetris, I’m thinking, ‘spin a plate’ to move [pieces] left or, ‘push a block’ to make it turn. So, it’s very, very confusing. And Tetris is very fast.”
But the biggest challenge Perri faces isn’t really the game, but rather convincing skeptical viewers that her endeavors aren’t fake — an argument she takes on daily. During her stream prior to speaking with Rolling Stone, there were dozens of commenters jumping in to accuse her work of lacking credibility. It’s easy to understand why viewers might rebuke her claims at face value, though Perri tries to maintain transparency with eye-tracking data and her brain activity being mapped in real time on-screen.
Representatives from Emotiv confirmed to Rolling Stone that the implementation is both possible and relatively straightforward compared to more sophisticated uses of the tech, and that Perri’s feats are genuine to the best of their knowledge based on conversations with the streamer. Although, even a direct statement from company scientists is unlikely to quell doubt.
Yet Perri accepts that there should be healthy skepticism of what she’s accomplished.
“Ninety nine percent of people are really lovely and really supportive,” she says. “The main criticisms I get are that I can’t prove it, and that I’m on the internet, which is valid. The one I see a lot is that multi-million-dollar companies can’t do it, so how come this random on the internet can do it? First of all, they can. And second of all, it’s different.”
But being a woman on the internet, much of what the streamer has to face is rooted in the internalized misogyny of those who think she’s simply incapable of the sophisticated coding work she’s doing, or even playing Elden Ring at all.
“People will say my boyfriend is playing for me,” she says, “There’s a boy under the table. Always under the table, which is quite funny.”
To Perri, much of the criticism of her EEG playstyle also stems from a broad misunderstanding of psychology and the science around the technology.
“Science can be one of those things [where] people love throwing jargon out there and confusing everyone to make themselves sound smarter,” she says. “And there’s less people who are actually interested in learning it.”
As of this reporting, Perri has just beaten the third boss of Shadow of the Erdtree, Messmer the Impaler, one of the toughest challenges yet for her. Beyond Elden Ring, she hopes to use her streams to spread awareness of the work that can be done with EEG for accessibility, but she makes it clear that what works for her isn’t a real solution for most people with disabilities.
“It’s just very hard to use,” she explains, “And it requires so much dexterity just to put it on, even with your hands to put it on and set it up. I’m very fortunate to not have firsthand experience with not being able to play games conventionally, but I feel like it would be more stressful and more upsetting.”
Perri points toward a general lack of funding for research groups around accessibility as a key factor in the lack of meaningful breakthroughs in the field and is cautiously optimistic about potential advancements like Elon Musk’s experimental Neuralink. For now, she’s doing her part by working informally with Emotiv to provide case studies and feedback that can be used to improve the functionality of their devices and, hopefully, open new ways to help people with disabilities. Right now, however, the programs she uses aren’t applicable to many neurological disorders, but the data can help.
“Just letting people know that it even exists is a pretty good goal for me,” she says. “I want to make it as good as possible so that, potentially, people could imagine a use case for accessibility.”
