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.

Windows Notepad is a simple text editor that has been around since the 1980s. This software commonly allows users to create and edit basic text documents.

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." ...

Most code editors are similar to notepad.exe in that they are "text editors", but unlike notepad.exe they have functionality built into them to send the code into the compiler.