MD System

The Moon Disc System (ムーンディスクシステム, mūndesuku shisutemu), or the MD System (MDシステム, MD shisutemu), is a game mechanic in moon which allows the player to play different kinds of background music throughout their trek in the order they select them. Each track comes in the form of a "Moon Disc", or "MD" for short. There are different ways to obtain them, but the main source of MDs are sold by Burrn. There are 36 MDs to collect in total and only 9 tracks can be set to play at a time.

The majority of MDs were commissioned and preformed by various indie artists. Each MD gets displayed by it's own unique jacket along with track and artist name.