A modder has made Doom 2 playable in the DOS version of Doom 2. By means of an exploit, he managed to make the classic within the shooter genre playable in the same game, with both games running simultaneously.
Modder and Youtuber kgsws uses an exploit in the DOS version of Doom 2 to run any code in the 1994 game. In the command
SpawnMapThing baked into a specific piece of vulnerable code, namely the ‘status code’ of a given object that normally describes the state of the object. Because of the vulnerability, this code can be manipulated in such a way that any code, for example Chocolate Doom, can be executed instead. The necessary code shared the Youtuber on GitHub.
The discoverer emphasizes that the exploit only works in the DOS version of Doom 2, not in all later ones ports of the game. “This is a good thing,” he writes under the video, “because you don’t want code execution vulnerabilities in modern systems.” After all, a hacker could also run malware via the vulnerability.
The Doom-in-Doom trick opens up a new era of Doomception. In the meantime, it has become an internet meme to get Doom running on all kinds of platforms not intended for that purpose. Think the Nintendo Game & Watch, motherboard firmware, the Trådfri Ikea lamp and a modified chainsaw affectionately known as ‘Painsaw’. As far as we know, however, it is the first time that Doom can actually be played in Doom. At least, Bethesda made Doom and Doom 2: Hell on Earth from 1993 and 1994 as easter egg already playable in 2020’s Doom Eternal.
Update, 8.25 pm: The original post claimed that the original Doom was made playable in Doom 2. In fact, it is about Doom 2 in Doom 2. The article has been adapted accordingly. Thanks to RustFreeSteel.