Boss Before



Boss Waiting Room (as named internally) is an atmospheric, eerie ambience in Metroid: Samus Returns. Composed by Daisuke Matsuoka, it is used four times during the game, as a lead-in to the battles with the first Alpha, Gamma and Zeta Metroids. The theme is rather repetitive when listening to the full version, but ingame is only heard for a few seconds before the respective Metroid appears. It is also heard in the post-credits ending. It does not play when Samus first encounters an Omega or Larva Metroid, or before she confronts the Queen Metroid.

The theme can be heard here.