Diablo

Diablo is a game universe created by Blizzard Entertainment. Unlike StarCraft and the original Warcraft games, Diablo is purely RPG.

The Secret Cow Level
One of the more well known aspects of the original Diablo game was something that didn't actually exist. Rumors started of a "cow level" with varying instructions or ideas on how to enter such a place and what existed in this level. Desptie Blizzard's claims to the contrary, such rumours persisted, individuals even creating fake screenshots. The issue was finally laid to rest in StarCraft, where the cheat for instant victory is to type in "there is no cow level".

Ironically enough, a Secret Cow Level was created for Diablo II anyway.

Other References

 * The Arbiter, if clicked on enough times, will state "we seek a soul in search of answers." This is a line taken from Diablo. The Observer will react similarly, albiet "I sense..."
 * Another quote from the Observer is "That sounds like a... a HUGE, GARGANTUAN, SWOLLEN, BLOATED MUSHROOM!" This is taken from the Diablo character of Grizwold.
 * Keeping in with the mushroom theme, one of the worlds of StarCraft: Ghost features large mushrooms as well.
 * The setting of the Diablo series is a world named Sanctuary. A region of Shakuras in StarCraft is named likewise.
 * A battle.net multiplayer mission for StarCraft is named "Diablo".