Situation I experienced: each time I exit the multiplayer menu or start up the game the starting song starts playing and the intro screen(black screen with a gray circle in the middle) fades in and out as normal, but if I press "Esc" before the intro screen has finished fading in and out then it immediately switches to the main menu(screen with the game title) and the audio continues playing as normal as if the intro screen was still fading in and out. It is definitely not a major problem and might not be a bug, but just in case it is a bug then now you know.
#An unintended main menu feature?
hollow orchid