The project file holds every tape's audio, its placement, the mixer settings and the MIDI map.
Audio renders the full mix, with EQ, effects, mute and solo. The MIDI file has one track per tape, with a note each time its clip comes round (each tape's note is set on its deck card), plus its volume and balance.
In this viewer, WAV, MP3 and MIDI files arrive inside a .zip because the viewer only hands over certain file types.