I'm playing Call of Duty: WWII on my Xbox One, and my kill/death ratio (the number of times I kill others versus the number of times I am killed) is above average. In Team Deathmatch and Kill Confirmed matches, I get second place with a 21/14 K/D ratio, first place with 18/15 , and fifth place with 14/11 . It's the first time I've played Call of Duty: WWII multiplayer, meaning I have no knowledge of map layouts or muscle memory for the various guns, their firing rates, and recoil. But I'm able to lead targets as they run for cover with ease. When an enemy gets the jump on me, I'm able to quickly adjust my aim and take them out first.

Call of Duty multiplayer has a reputation for being a meat grinder. You spawn into a match, get a kill or two before you die if you're good, then respawn, rinse, and repeat. It's been years since I played a Call of Duty game on consoles, so I'm out of practice and should be tender for the grinder, but I'm kicking ass.

The accepted wisdom that a mouse and keyboard player will always have the upper hand over a player with a controller has gone largely unquestioned for decades, but game developers and console manufacturers have been either unable or unwilling to block devices like the XIM.

Many players would consider what I'm doing cheating because—they would argue—a mouse allows me to aim more quickly and precisely than the thumbstick players use to aim on standard controllers.

I'd love to say that I'm just that good, but the truth is that I'm using a device that allows me to play with a mouse and keyboard (and other input devices that aren't officially supported), instead of a standard controller, which is not something I should be able to do on a console. The device, called XIM Apex , costs $100 and looks like a USB stick and hub that allows me to plug my PC’s mouse and keyboard into an Xbox One (or PlayStation 4) while my competitors and teammates presumably play with regular Xbox One controllers.

"I just want to take the time to thank this company and the community for making gaming possible for me," a user named Kollietheclaw wrote on XIM's official forum in 2018.

Using the XIM definitely made me, someone who grew up playing games like Call of Duty with a mouse and keyboard on PC, a better player. But it also made me question if the accepted wisdom about the supposed advantages of mice is actually true, or just another form of gatekeeping that the video game community is so unfortunately known for. More importantly, talking to the XIM's creator and people who use the device made it clear that—even if it were unequivocally a form of cheating—banning it would be devastating to some of the XIM's biggest fans: people with motor disabilities.

"XIM is Unauthorized Hardware. You are therefore dishonestly violating a rule , which is the DEFINITION of cheating," wrote another player on the Apex Legends subreddit in a thread titled "It is inarguable that using XIM on a console is cheating," citing Sony's and Microsoft's terms of service, both of which prohibit the use of unauthorized software and hardware.

"I don't care what your sensitivity is. Analog movement is not the same as mouse movement. It's your entire arm span vs an inch radius analog. You can make minute and incredibly precise changes on mouse that simply can't be emulated on analog," wrote one player on the PlayerUnknown's Battlegrounds subreddit under a thread titled "For the 10 Billionth time, yes, Mouse and Keyboard IS CHEATING."

Kollietheclaw explained that they have a rare congenital condition called symbrachydactyly, which means they were born with missing fingers, or short fingers which may be webbed. "Because of this defect I've never been able to play console games with my friends and I've never been able to afford a PC any more than a stock Walmart pc.....the deformity is on my left hand....I can use an analog but any left side button isn't possible because I only have a thumb and a half pinky," they wrote.

"Currently, we cannot do anything about players using input conversion devices to use Mouse and Keyboard on console," he wrote. "However, we have put serious research and development against this problem and we're hoping to have a solution to what we consider to be unfair circumstances. This is a priority for us and we're trying to combat this through technology and policy."

"The Overwatch team objects to the use of mouse and keyboard on console," Jeff Kaplan, Vice President of Blizzard Entertainment and _Overwatch’_s game director, wrote in 2017 . "We have contacted both first-party console manufacturers and expressed our concern about the use of mouse and keyboard and input conversion devices."

In 2017, Kotaku's Cecilia D'Anastasio reported about the controversy around the XIM 4 (the version of the device released before the XIM Apex) in Overwatch, Blizzard's popular first-person shooter. The outrage from console Overwatch players about their competitors using the XIM prompted a response from Blizzard.

"I think it's unfair if someone plugged in a [mouse and keyboard] to their Xbox," John Glenn, who competed in Halo for the last couple of years as a coach and has a _Halo_-themed YouTube channel , told me in an email. "This gives a distinct advantage to the player who is using a different input, since their opponents aren't expecting it and may not know how to deal with those advantages. I'm okay with this resulting in a temporary ban of some form and then escalating to a permanent ban after so many offenses."

However, Mark, the creator of the XIM Apex, told me that this method wouldn't catch his device, which connects a mouse and keyboard to the console via an official, regular controller. Mark didn't want to share his full name because he fears harassment from players who consider the XIM Apex a form of cheating.

Microsoft didn't explain exactly how its API works, but Steve Spohn, COO of AbleGamers, a non-profit focused focused on improving the lives of gamers with disabilities, told me in a phone interview game developers can block specific devices. USB devices have unique IDs. For example, the mouse I'm using, a Logitech G502, has the ID of UD:046d:c07d . An Xbox API could conceivably give developers the ability to block it, or any other ID that isn't whitelisted.

Despite being widely known and hated, game developers and console manufacturers haven't cracked down on the XIM Apex like they've cracked down on other forms of cheating .

Sony didn't respond to multiple requests for comment, but the company does promote the TAC PRO M2 , an officially licensed, XIM-like mouse and keyboard duo for the company’s PlayStation 4 and PlayStation 3 consoles. The TAC PRO M2 works with all games, just like the XIM, and is marketed specifically for shooters, but has received mixed reviews. I tested the TAC PRO M2 on PlayStation 4 by playing Apex Legends and found that while it was much easier to get started—all you have to do is plug it in—it didn't work nearly as well as the XIM Apex.

“Microsoft does not recommend the use of unauthorized third-party products and applications and cannot guarantee compatibility with Xbox devices," a Microsoft spokesperson told me in an email after I asked the company whether Microsoft gives developers on its platform the ability to block devices like the XIM. "Xbox provides an API for developers that detects the use of unauthorized devices, and it is up to individual developers to decide how best to implement within their games to ensure a fair and balanced gaming experience. While we can offer guidance as the platform, developers decide what’s right for their games. We have nothing further to share at this time.”

Mark speculated that console makers and game developers would be able to detect a player who is using a XIM Apex by looking for input behavior that would indicate they're using a keyboard. A player who's using the WASD keys on a keyboard to move can only move in eight directions (up, down, left, right, and four combinations of these directions for diagonal movement), while a player with a standard controller and thumbstick has 360 degrees of movement. However, Mark said this method could lead developers to accidentally block not just the XIM Apex, but other, uncontroversial accessibility devices.

"The CronusMAX uses stealth technology and is 100% fully undetectable online due to how we use an original controller for its security ID," CronusMAX's website reads. "Unlike with some other adapters, the console believes that you are gaming with a controller meant for the console you are playing on and any scripts or mods simply mimic button, stick and trigger presses/movements automatically...We do recommend you don’t go too crazy though, as other players may scream at you for owning them so easily ;)"

"The console still talks directly to its controller—there is no USB ID (i.e. VID or PID) that can be used for detection," Mark told me in an email. "XIM will pass through all USB communication that’s not input-related to and from the controller (this includes audio, security communication, etc.). But, when the console asks for input, XIM replies on behalf of the controller. XIM will ask your mouse, keyboard, and controller for input and 'translate' that into controller state and send that back to the console when asked."

"That's why I never ever advertise the XIM as a PC equivalent experience," Mark said. "It is simply not that. It just allows you to use the input device you prefer. It will not turn you into a gaming god."

Mark said these comments come from people who have never actually used a XIM. If they did, he said, they would understand its limitations. Critically, Mark explained, the XIM doesn't allow a user to exceed the maximum turning speed that's baked into the console version of the game by the developer. In the PC versions of Call of Duty games, for example, players can perform 'flick shots.' With the mouse sensitivity turned up, they can flick their mouse to quickly aim and take out a target (this is also how you'd pull off a sick " 360 no scope headshot " on PC). But on consoles, even with a XIM, there's a maximum turning speed, so a player with a XIM and a mouse can't turn around and aim at an enemy behind them faster than a player with a normal controller.

"It's very common now when you go on forums for games like PlayerUnknown's Battlegrounds or Fortnite and now Apex Legends, there's a lot of people complaining that, if they die quickly, the other person was doing something that they feel they shouldn't be able to do, and they must be using a XIM," he told me in a Skype call.

Mark claims that the reason his device is better than the competition is the primary proprietary software behind the XIM, which he calls "smart translators."

With the exception of the turning speed limitation, which I only noticed when I was looking for it, moving around in Call of Duty: WWII with a mouse and a XIM felt like I was playing the game on PC. I had to drag my Xbox One to my computer desk, create a nasty nest of cords, and spend a couple of minutes configuring the XIM Apex with its cheap-looking companion app. But once I was set up and running, I sometimes forgot that I was playing on an Xbox One and not a PC.

Mark said that he doesn't even consider mouse and keyboard adapters like CronusMAX and Titan as competition because they promote and enable macros and scripting, software that allow users to perform several actions, or actions that are physically impossible for any human, with a single button press. Mark considers macros cheating and refuses to support them on XIM on principle.

One of XIM Apex's competitors, the KeyMander, promises to allow players to "harness the speed and precision of a keyboard and mouse to destroy the competition," and "dominate your favorite games like Call of Duty, Battlefield, and Halo, and leave those controller players at the bottom of the scoreboard." CronusMAX says it gives players an "edge," and offers "specialized scripts that will smoke the competition."

Mark claims that, unlike his competitors, the XIM's smart translators use machine learning to automatically reverse engineer these behaviors, and create unique aiming behavior settings for each game to make it feel more like a PC game when using a mouse. This is why XIM Apex users have to choose what game they're playing from the companion app before they start.

There are a handful of Xbox One and PlayStation games that are designed to natively support a mouse and keyboard that users can plug into the consoles' USB ports. Every other game that players want to control with a mouse and keyboard requires an external device like the XIM that can map a console game's complex aiming behaviors to mouse movement.

"Deadzones," for example, are small areas around the center of the thumbstick that do not respond to movement in order to prevent jitter every time a player slightly touches the thumbstick. Every game also has finely tuned "acceleration speeds," meaning that the player's aim will move faster when they move the thumbstick closer to the edge. These, and other non-linear behaviors make games like Halo feel good to play with a controller. When you play a new first-person shooter on console and are not enjoying the way it controls, that's probably because you're not used to, or simply dislike one of these behaviors.

From the player’s perspective, it might seem like playing Call of Duty on console is effortless. But behind the scenes, there is a complex array of software-driven solutions that make it easy to play with a controller as opposed to a mouse and keyboard.

This is also why Mark insists that using a XIM isn't cheating. The device isn't trying to let users do something that a controller can't. It's trying to understand how that controller works, and let users choose the input methods they like best. In other words, the XIM Apex works well precisely because it's playing by the rules of the game's aiming system, not because it's circumventing them.

“This is the most complicated, advanced solution to the problem," Mark said, referring to the XIM's smart translators. "It moves the burden of this process offline, to simplify it for everyone."

This is in contrast to a device like the TAC PRO M2, which technically worked when I plugged it in, but that made my aim worse than it was with a mouse on a PC, or with a controller. The TAC PRO M2 allowed me to use its companion app to finely tune how the device handles deadzones and acceleration speeds, but after hours of fiddling and watching other players' configurations on YouTube, I never got it to a point where it'd be worth using over a normal controller. Other devices, like KeyMander and CronusMAX, also require users to manually fiddle with deadzone and acceleration settings.

"XIM uses an offline learning process in order to understand how the game's aiming mechanics function," Mark said. "The system will essentially play the game itself, learn how the game behaves, and adjust so every game feels right with a mouse."

"Theft is a serious problem, especially with devices like this," he said. "People copy my competitors and just release the same device under a different name, so the XIM is pretty locked down."

Soon after Engadget's story was published, people started emailing Mark to ask if he could make something that would allow them to play Halo 2 with a mouse in the same way that his setup made it work with a Wii Remote. More than a decade later, XIM is now a company of "about five" people, according to Mark. He declined to share how much the company makes, but said that he doesn't need a day job anymore, though he keeps it because he likes the people he works with. Mark said the XIM's software is encrypted, that its circuit board is obfuscated, and that the device is assembled in the US because he's worried someone will steal his invention.

The desire to control console games with input devices that aren't officially supported is how the XIM got started in the first place. Back in 2006, Mark was enamored with the Wii Remote, a novel, motion-based controller for Nintendo's Wii. Using an elaborate setup which involved a PC, a PlayStation 2-to-Xbox 360 controller adapter, and custom firmware, he was able to control Halo 2 on the Xbox 360 with the Wii Remote. He uploaded a video of this Frankenstein setup to the internet, which was covered by Engadget .

"A XIM, in the end, can't do anything that a standard controller can't do," Mark said. "It's just a different way to interface with the game."

Spohn uses a head tracking input device, TrackIR , which lets him move his head instead of pressing keyboard keys. He also uses a XIM when playing on consoles.

"The adaptive controller is great and I'm so proud of it, but it's made for people who need certain help," Spohn, who helped create the Xbox Adaptive Controller, told me.

Last year, Microsoft announced the Xbox Adaptive Controller , a flat, $100 Xbox One input device with two big buttons on the front that also allows users to connect a number of specialty input devices for people with motor disabilities. It is the single most accessible gaming controller ever made , but even the Xbox Adaptive Controller doesn't support a mouse.

"I get letters all the time from parents thanking me," Mark said. "I made custom changes to the XIM just for them, hardware compatibility changes, allowing people to use devices they need to game."

Mark told me he also hates using thumbsticks, so he understands the demand. Some people who usually play games on PC are used to only playing with a mouse, but want to play with their friends who are on consoles. Others want to connect other devices that are not currently supported by consoles, like some fighting game sticks or flight sticks. Some people, Mark learned, use the XIM to connect special accessibility controllers to their consoles.

The idea that a player with a mouse and keyboard will always have an edge over a player with a console controller in a first-person shooter has existed since first-person shooters arrived on consoles. A lot of the baggage associated with the issue of using a mouse and keyboard on console simply comes from the fact that the first-person shooter genre was popularized on PC, and some gamers always recoil when the games they love are made more accessible in order to reach a wider audience.

Spohn told me that over the years AbleGamers has heard anecdotal evidence of players being cut off from games for using accessibility software. He said that he heard from players who've been banned by the MMO Jade Dynasty's anti-cheat software for using eye tracking solutions and on-screen keyboards. The most recent case he remembered was that PlayerUnknown's Battlegrounds players were banned from the game for using Dragon NaturallySpeaking, a speech recognition software.

"My stance has always been that if you can buy a technology that allows someone with a disability to play with a reasonable cost, and if someone without a disability says they have to buy it to be on the same level, it's easier for them to buy the device than cut out disabled gamers," Spohn told me.

"Not long ago, we helped a girl who lost her arms in an accident, loved playing Xbox, and the only way she could was to use XIM. Worked great," he said on Twitter in 2017.

I have always preferred to play games on a PC, and am far more comfortable playing shooters with a mouse and keyboard. But I'm not sure if a mouse and keyboard are inherently superior to a console controller, or if this is just a maxim players have accepted—unchallenged—and one that is tied to a broader feeling of superiority among PC gamers who self-styled themselves as the "PC Master Race."

When writing this story, I remembered the release of Quake III Arena on the Dreamcast in 2000, and how it allowed players to use a regular Dreamcast controller or an official Dreamcast mouse and keyboard. A review from IGN at the time noted that the matchup between the two input devices was unfair, setting the tone for the debate that we're still having to this day.

"You need a mouse and keyboard," the review said. "I don't care how much it pains you to suck it up and get a clue about FPS gaming, but if you want to compete in this or any other title like it, you will want to go ahead and get your hands on the peripherals mentioned above...Aiming is far too difficult with a controller, and though you can play with one, don't expect to hold your own with any DC [Dreamcast] gamer who is using a mouse and keyboard."

I'm not positive that this would be the widely-accepted sentiment in video games it is today if history had unfolded differently, and the first-person shooter genre was born on consoles. The video game community is filled with commonly-held beliefs about certain input devices being better than others that seem to be largely based on tradition.

Fighting game fans love to play with fighting game sticks because they resemble the arcade machines that the genre came from, but SonicFox, one of the best fighting game players in the world, uses a controller. PC gamers love the tactile feel of mechanical keyboards because those were the kind of keyboards that were around in the early days of PC gaming, but kids who are growing up today will absolutely hand you your ass in Fortnite by tapping away on an iPad.

When I played Call of Duty: WWII and Apex Legends with the XIM Apex, I definitely played better than I would have with a controller, but that might have less to do with some inherent advantage of mice and keyboards than it does the hundreds, if not thousands of hours more I’ve put into those types of games on PC than on console. Additionally, while I was playing well, I wasn't annihilating the competition. I wasn't even doing better than I normally do on PC when I play against other people who are using a mouse and keyboard.

Like Mark noted, the fact that I was playing with a mouse and keyboard while other players had controllers did not turn me into a gaming god. It just made me comfortable.

THE CURB-CUT EFFECT

There's no doubt that first-person shooters, and many other competitive video games, favor players with fast reflexes and good hand-eye coordination, but that's far from all that goes into being a good player. Learning the layout of a map, how different abilities interact, and how to—for lack of a better term—play the hand you are dealt at any given moment is just as important as good aim. It's fun to watch professional players pull off difficult shots in the most competitive eSports events, sure, but communication among teammates, strategy, matchups, and other elements that make up what players call the metagame is just as interesting. I sincerely doubt that eSports, and shooters more broadly, would even be a phenomenon if they were just an aiming competition.

If it's the integrity of the sport that players are worried about, professional eSports events have the right to ban devices like the XIM, and the competition rules I've looked up already do. The Call of Duty World League Handbook, for example, gives organizers the right to "inspect, approve, or deny all Player-owned equipment." The Halo Championship Series Handbook says that "No forms of cheating will be tolerated," including "software modification" and "hardware modification."

Spohn told me that even if a device like the XIM, which enables people with motor disabilities to play a video game they wouldn't be able to enjoy otherwise, gives able-bodied people some kind of advantage, it should still be allowed.

"If this was the only way for you to play then you'd want someone fighting for you too."

Able-bodied people often benefit from solutions created for people with disabilities. This dynamic is so common it has a name: "the curb-cut effect." The name refers to the sloping curbs you'll find at every intersection, which allow people in wheelchairs to more easily move from the road to the sidewalk. In early 70s Berkeley, California, when curb cuts weren't as common, disability rights activists created their own makeshift versions under the risk of arrest to prove how much they're needed.

"Then a magnificent and unexpected thing happened," Angela Glover Blackwell, founder in residence at PolicyLink, an institute dedicated to advancing economic and social equity, wrote in 2017. "When the wall of exclusion came down, everybody benefited—not only people in wheelchairs. Parents pushing strollers headed straight for curb cuts. So did workers pushing heavy carts, business travelers wheeling luggage, even runners and skateboarders."

I have a hard time imagining why the average player would care if another player was using a XIM, especially considering that for many, there's no other way to play.