I'll start with perhaps a brushed metal finish... I do not think this project needs to have 'glossy' or 3D-type buttons... These beasties scream 'Hey look at me' and will 'distract'. After all, you do not want the player to crash, because their attention was 'drawn' to the fancy buttons... lol
Quick question: Regardless of the 'style', will you be wanting a duplicate 'clicked' button? (ie: slight colour change to indicate clicked)
J