Security researcher Sick Codes teamed up with Doom modder Skelegant to run the game on a John Deere tractor screen and demonstrated the gameplay at the Def Con hacker conference in Las Vegas.

In a video posted by Sick Codes, you can see the game rendered as an overlay over John Deere’s user interface. Sick Codes states that the whole process took months and involved jailbreaking the Linux system used on the John Deere 4240 tractor. The Doom game itself was previously modified to take place in a cornfield where the player mows enemies with a tractor.

Interestingly, Sick Codes didn’t hack the tractor just to run Doom. It has also developed and introduced a new jailbreak that provides root access to the tractor system. This exploit could potentially help farmers bypass software locks that prevent them from repairing their tractors themselves; this was previously criticized by John Deere.

How to hack John Deere software

To jailbreak a John Deere tractor, Sick Codes accessed 1.5GB of technical documentation that dealers use to identify and diagnose faults. Additionally, the hacker found a way to gain root access by soldering the controllers directly to the tractor’s circuit board. After all, rooting isn’t all that easy without the proper hardware, but Sick Codes states that “a vulnerabilities-based tool can be developed to easily jailbreak.”

John Deere blocks tractors stolen from Ukrainians

John Deere’s technological control over its tractors goes beyond repair. Earlier this year, the manufacturer remotely locked its equipment after the Russians stole it from farms in Ukraine during a full-scale military occupation. In response to increased pressure from politicians, John Deere announced in March its initiative to make its software available to independent repair shops.