For centuries Earth has used Mortal Kombat to defend itself against the Outworld's emperor, Shao Kahn.
But Kahn grows frustrated by failed attempts at taking Earth through tournament battle.
He enacts a plan which began 10,000 years ago.

During this time Shao Kahn had a queen.
Her name was Sindel, and her young death was unexpected.
Kahn's shadow priests, led by Shang Tsung, make it so Sindel's spirit would someday be reborn:
not on the Outworld, but on the Earth Realm itself.

This unholy act gives Shao Kahn the power to step through the dimensional gates and reclaim his queen,
thus enabling him to finally seize the Earth Realm.

Upon breaching the portal into Earth,
Shao Kahn slowly transforms the planet into a part of the Outworld itself.
Kahn strips the Earth of all human life: claiming every soul as his own.
But there are souls which Kahn cannot take.
These souls belong to the warriors chosen to represent Earth in a new Mortal Kombat.
The remaining humans are scattered throughout the planet.
Shao Khan sends an army of fierce Outworld warriors to find and eliminate them.