A partial list of color-coded passwords to skip levels includes (see for the full set): Light Blue, Brown, Dark Blue, Green, Green Egypt 2-1: Red, Brown, Green, Dark Blue, Light Blue Castle 3-1: Red, Green, Red, Dark Blue, Light Blue Spaceship 4-1: Dark Blue, Red, Green, Green, Red Final Boss: Light Blue, Red, Green, Dark Blue, Red Gameplay Features & Preservation

While "registration key" might be a remnant of old-school software gaming (perhaps a nod to the classic platformer *Bud Redhead: The Time Chase"), applying this concept to offers a fascinating look at a specific demographic.

As a friendly assistant, I need to clarify that "Bud Redhead" doesn't seem to be a widely recognized term or a specific product/ software that I'm aware of. However, I'm assuming you might be referring to "Budweiser" or perhaps a different context.