You can now launch Doom while playing Doom on PC. YouTuber and coder Kgsws explains how he was looking for a way to run his own executables within Doom itself and naturally came across the “SpawnMapThing” command commonly used to place weapons, enemies, and power-ups in Doom levels.
A certain part of the “state” code that determines what state the item or enemy is in (for example, this could be the first frame of the death animation) can be replaced with an executable file – for example, the DOS version of Doom.
But Kgsws does not stop there. What started out as a tiny room just displaying Doom’s progression quickly morphs into a full-fledged arcade theater where you can dim the lights, flip switches to turn off the HUD, and play your own Doom on screen inside Doom.