Modders are an industrious bunch, with 1993 classic 'Doom' one of the most-modded games of all time.

The game has run on everything from pregnancy tests, fridges, thermometers, and ticket validators, and now a modder has managed to get the game running inside 'Doom II'.

'Doom' was a massively influential title in the first-person shooter genre, and the game is now used as a litmus test among members of the modding community to determine if something can be hacked.

The 1993 game is now running inside 'Doom II', and this incredible and brain-hurting feat of engineering was pulled off by the talented YouTuber kgsws.

From a technical standpoint, the hack uses an exploit in the DOS version of 'Doom II', and uses a modern port of the original 'Doom' (dubbed 'Chocolate Doom') to get it running within the game.

This 15-minute YouTube video goes into more detail, and it an impressive feat and testament to the ingenuity of modders.

The original 'Doom' runs in 'Doom II' as an animated texture, and only applies to the original DOS-based 'Doom II', but the feat itself is still massively impressive.

'Doom' is projected onto the wall like a film, and players can hop in and out of the game ala 'Super Mario 64', which will spark an existential debate within you about whether you are controlling yourself or controlling someone within a game within a game.

2020's 'Doom Eternal' is an absolute graphical beast of a game that gave the new HP gaming laptop a run for its money, and knowing modders, it's only a matter of time before they get 'Doom Eternal' running on a Nokia 3310.

For gamers who want to see this mod in action, the link can be downloaded on Github.