Depends what you mean by "beginning". The Intro scene is "The Tyrant" by Kevin MacLeod. The "intro" (opening credits) is "Hold On" by Myuu. The music on the main menu is "Take Me Higher" by CJbeards - his music is used fairly extensively, and can be found on youtube (just search youtube for CJbeards, he makes some good stuff).
Also note: all music is available (song name and artist) via the music player on the main menu.