MIDI music file (Corridor 7, Blake Stone, Wolfenstein 3D, Spear of Destiny)
IMF is an audio file format created for id Software. IMF files contain musical notes, and are used to send music data for playback on AdLib sound cards, which are generally used in video games. IMF files are similar to MIDI files, since they don’t contain sampled digital audio.
MIME: audio/imf, application/adlib
Learn more about .IMF files:
Learn about id Software products on Wikipedia.
Search on IT Knowledge Exchange for .IMF-related questions.