If you want to unlock Palpatine the long way, then you have to get every system under Republic control. If you want to use the cheat code, enter 5C62YQ. To get the emperor in Lego Star Wars III, get all the minikits in the Geonosis Arena (aka the prologue). Once you do that, take the elevator in the medical center on the Republic starship, star-destroyer hubworld. You will see tanks with characters floating in them. To get the empreror, go to the tank with the emperor, and press \”release\”.
This will release the emperor, and you will be able to buy him. The emperor (or Darth Sidious, as he is called in the game) will cost 275,000 studs (the currency in the Lego video games).
Master Yoda : I hear a new apprentice you have, Emperor, or should I call you Darth Sidious? Emperor Palpatine : Master Yoda. you survived. Master Yoda : Surprised?
Emperor Palpatine : [grinning] Your arrogance blinds you, Master Yoda. Now you will witness the full power of the Dark Side! [He strikes Yoda to the floor with Force Lightning] Emperor Palpatine : I have waited a long time for this moment, my little green friend. At last, the Jedi are no more. Yoda : Not if anything to say about it I have! [Yoda Force-flings Palpatine across the room and across his desk] Yoda : At an end, your rule is.
And not short enough, it was! [Palpatine leaps towards a door in panic, but Yoda leaps in and blocks his way] Yoda : If so powerful you are. why leave? [ignites his lightsaber] Emperor Palpatine : You will not stop me! Darth Vader will become more powerful than either of us! [ignites his lightsaber] Yoda : Faith in your new apprentice, misplaced may be. As is your faith in the Dark Side of the Force.