Red, green and blue are the primary colours of the additive (projected) colour system while cyan, magenta and yellow are subtractive (reflected) colours. In the quest you will find various doors which have two colours attached to them, you are required to use prisms, mirrors and coloured crystals to direct a beam of light which is the correct colour to the various doors to unlock them. The doors will only unlock when they are hit with a beam of light which is complementary on the colour wheel. So for instance, the magenta door must be unlocked with a green beam of light.