Go to option screen on any level and c-up c-right a d-left and then z this will grant you on easy 1-5, that's because it only goes up to that many on easy on normalit will give you all the levels. Also it will give you a list of codes for cheats such as these. Invincibility, infinte lives, unlimited secondary weapond and a list of what secondary weapon you would like. It will also give you a list of "bosses" such as the Dracula's