Winmiditoqwerty.exe
The program maps specific MIDI notes to specific QWERTY keys. For example, pressing "Middle C" on a MIDI keyboard might trigger the "A" key on the PC, which the virtual piano software interprets as a specific note.
The most famous part of the legend involves a streamer who tried to "outplay" the program. During a live session, the software allegedly began "answering" his melodies. When he played a happy tune, it responded with a distorted, minor-key version of the same song. The stream cut to black when the software mapped every single key on his keyboard to the "Delete" function, erasing his operating system in real-time. Winmiditoqwerty.exe