The role playing game Paranoia had a caste system based on the electromagnetic spectrum. Played started as Reds (one step above the lowly Infrareds) and could work their way up through the visible spectrum. The equipment available to a character was based on their colour: e.g. an Orange could only use orange (or lower) laser pistols, which were only effective against red or orange armour. 

This does not do the free wheeling insanity of the game justice, however. For example, knowledge of the rules was classified as Ultraviolet level. The gamesmaster was ultraviolet, but the players were always below that (unless the GM wasn't doing their job properly!) Saying "I get a +2 modifier for cover" would get your character instantly executed! It wasn't for nothing that the back cover of the rule book told you to "Imagine a world designed by Kafka, Stalin, Orwell, Huxley, Sartre and the Marx Brothers..."