The Great Game is the eternal, all-consuming rivalry waged between the four great powers of Chaos. Bound by their very natures to oppose one another, the Chaos Gods can never win a final victory, for the triumph of any one would starve the others of the emotions on which all of them feed. Instead they contend forever, each seeking to expand its own portion of power at its rivals' expense.
This cosmic contest is fought not only in the churning depths of the Warp but through every mortal pawn the gods can claim. Champions are raised up and cast down, cults are set against cults, and entire wars in the material universe are engineered as moves in a game whose full shape no mortal mind can grasp. Khorne despises the sorcery of Tzeentch, Nurgle and Slaanesh are locked in bitter enmity, and alliances between the powers are always fleeting and treacherous.
Only rarely do the gods set aside their feud, uniting briefly beneath the banner of Chaos Undivided when a prize is great enough to be worth sharing. Such moments are terrifying, for a Chaos that acts with one will could unmake the galaxy. Far more often, it is the very disunity of the Great Game that keeps the Dark Gods from overwhelming reality entirely.