If he had become empire and beaten Obi Wan on the mustafar system (I think that is how it's spelt) then he would have had to get Padme, she would die from giving birth (maybe) and Anankin would raise Luke and Leia up and teach them the ways off the Dark side hence they would become very very powerful hence complete dominance over the galaxy meaning that the Rebel alliance loses and the dark side reigns victorious.
Originally posted by steverulesYou don't mention Palpatine, I take it your discluding him?
If he had become empire and beaten Obi Wan on the mustafar system (I think that is how it's spelt) then he would have had to get Padme, she would die from giving birth (maybe) and Anankin would raise Luke and Leia up and teach them the ways off the Dark side hence they would become very very powerful hence complete dominance over the galaxy meaning that the Rebel alliance loses and the dark side reigns victorious.
In that case I doubt Vader would be yet powerful enough to take on Yoda. The Empire would crumble, Padme (might) live, the twins would be Jedi under Yoda, and the rebellious Senators would take control of the Republic.