You've heard the concept of the "rat race," but how about a literal rat, racing through the hallways of Doom? One researcher named Viktor Toth ran an experiment over nearly six months, seeing if he could train a rat to run down a straight hallway in Doom by using a VR rig he built himself.
As Toth explained on Mindsoft, It took him about four months to build the VR rig for the rats, using a 3D printer, an iron, a drilling machine, and a set of screwdrivers. The main part of the rig is a large, round ball sitting on a base that allows the ball to rotate in place. There are also motion sensors taken from computer mouses that track the movement of the ball. The rat is then strapped into a harness on top of the ball, facing a large, curved PC monitor displaying the game. When the rat moves the ball in a specific direction, the game responds by moving the player in that same direction.
It's like a large hamster ball you put your pet in to let them run around the room, only in this case, the animal rests on top of the ball instead of inside, and the movement is tied into a video game. Toth also set up a sugary water release system for positive reinforcement to help train the rat to move on the ball through the hall.
The hallway itself was a straight hallway taken from the opening map of Doom 2. When the rat reached the end of the hallway, it was programmed to warp back to the start so the rat could keep going.
Toth used three rats for this experiment: Romero, Carmack, and Tom. The researcher says Romero, who loved eating grapes, ended up having the most success moving through the hallway. Eventually, after six weeks of training on the VR rig, Romero learned to run down the hallway pretty consistently. He was at first confused by the ball he was moving on, but later started to walk on his own. You can check out the full video of Romero running down the hall on YouTube — it's pretty cool to see.
Toth also toyed with teaching the rats to shoot enemies by lifting their paws, but he says the rats were never consistent at performing this action. So, what's the point of this? Well, Toth says running experiments using software, like a video game, can be much more cost-effective than a hardware-based experiment, like a maze.
"Once we can reliably train animals to play games, designing an experiment becomes a software problem instead of an often costly hardware problem," Toth said.
However, it seems there is still a long way to go to reach the idea of consistent software-based experiments. In this trial, after 11 days of VR training, Toth still needed to be there to help get the rats on and off the ball themselves.
If hearing about a rat running through Doom made you want to play the series yourself, check out our review of the latest DLC for Doom Eternal. Or, check out how the Doom series fares on our ranking of the best FPS campaigns of all time.
Logan Plant is a freelance writer for IGN. You can find him on Twitter @LoganJPlant.