There are so many good OSTs for games it is impossible to choose. Akira Yamaoka's work in Silent Hill comes to mind, along with Kelly Bailey for the Half-Life series. Lately, I am also really just enjoying listening to the music from Mystical Ninja Staring Goman, Bomberman 64, and Mischief Makers, among the classics like Donkey Kong and Mario 64 of course. So many good bops!