If I ruled world I would enslave humanity and demand that our top scientists find a way to travel to the legendary realm of Outworld. Once they figure out how to make contact with Outworld, I will allow Outworld's leader Shao Khan (or Onaga, depends on when we arrive) to merge his realm with our realm, which I have dubbed Earthrealm.
At this point in time I have achieved immortality. How? Fuck you that's how! And I will use my immense power to eliminate the current emperor of Outworld, thus taking control of the merged realms.
After a century of ruling with an iron fist, I will disappear for another century. Making people believe that I was only legend and no way real or ever make my return, giving them all a sense of security and hope. This, of course, is when I return stronger than anyone who has ever existed before me and reclaim my throne. Why? Cause I'm a sadistic fuck. Which will, in turn, lead to an Earthrealm rebellion. Now I lead the forces of Outworld and will fight the rebellion for an unknown amount of time.
In the end, a young warrior named Casey, who is a descendant of the legendary Nicolas Cage, will challenge me in a one round Mortal Kombat tournament for Earthrealm's victory and freedom. Naturally I accept, and after a long intense fight that destroys all of what used to be Houston, he will emerge the champion. Thus separating the two realms, and ending my long reign of terror.
Oh yeah and Rob Schneider movies will be illegal.