A long time ago, there was life on the surface of this plane. Human life, mostly, plus various spirits, elementals, demons and other sentients. They lived divided into nations; sixteen that we know of. Each of the teams we have today is named for one: Canis, Ursa, Cetus, Orion, Lacerta, Cepheus, Hydra, Vulpecula, Lynx, Corvus, Pavo, Delphinus, Lepus, Monoceros, Pyxis and Cygnus. They all had different cultures and customs, but they worshipped the same gods, and above them, the Old Man and the Old Woman -- the earth and the sun.
There came a time when the Old Woman grew angry; no one knows why. But in her anger, she threatened to burn away the surface of the plane. The gods, when they saw this, commanded all their worshippers to build a sanctuary that they would bless; a place to wait for the Old Woman's wrath to fade. It was a close thing, but the shelter was completed just in time, and the people were saved, at the price of being sunk deep into the Old Man's embrace.
But time passed, far more than the gods had claimed. And while the shelter had begun as a paradise, nothing lasts forever. Things began to fall apart and decay. The gods began to fade away, deprived of sustenance. Then, one day, a god named the Trickster, realized that his bride -- the Flowers -- had fallen deathly ill. So he found a plan to save her life, against her wishes: he held a game, pitting nation against nation. In that game, he grew desperate, and demanded human sacrifices in her name. And someone made them.
Flowers is insane, now. Dangerous, one of the worst. Trickster is dead; we denied him what he needed from us, our fear. And the Games go on.