Classic FPS Doom is running in Microsoft Notepad thanks to game developer Sam Chiet, who shared footage of the shooter project that has now gone viral ...

And people would use all those 50 rounds, they played five to six hours … You could use Notepad to [adjust some code and unlock] the entire game." ...

Over the decades, people have managed to get the original Doom to run on all sorts of interesting devices, and a fan ports the game to Notepad.