Spoiler Alert: This post contains information of one of the game's big secrets.
Easter eggs in Blizzard Games are a standard, and 'Diablo III' is no exception. The game's secret world has been discovered and it shows the sense of humor that Blizzard has about its products and its fans.
When 'Diablo III' was first shown, there was a bit of an uprising from some very outspoken fans regarding the look of the game. A rainbow in particular sparked the ire of these fans, causing countless threads online about the "toned down" and "whimsical" design.
Blizzard initially responded with an overly cutesy 'Diablo III' shirt, but the secret level placed in the game takes things even further. Titled Whimseyville, the area is full of rainbows, happy clouds, ponies and more.