There's a long-running joke in tech circles that gauges any device's power and / hackability with the simple question: Can it run Doom? id Software's famous FPS has been made to run on everything from a home thermostat to a printer, and seems to offer a pretty good indication of how far consumer technology has come in a relatively short space of time.
However, it would seem that we have now reached the end game; the point of no return. Someone has actually managed to run Doom within Doom.
The discovery has been made public by YouTuber kgsws (thanks, Gizmodo), and the hack technically makes use of an exploit in the DOS version of Doom II to get Chocolate Doom (AKA 'Vanilla Doom' – a modern port of the game) working within Doom as an animated texture.
The 15-minute video explains how the hack works and is well worth a watch if you like seeing games being broken or pushed to their limits. If you'd like to give it a spin, the code is live on GitHub, and you can find the required copy of Doom II on Steam.