- Make Vader playable for the rest of the game
- Add new hilts - lots
- Different (normal) lightsabre stances
- New sabre colours
- Increase Boss and enemy stats
- New skins/models - Roan Fel, Wilhuff Tarkin, Thrawn, etc.
- New clothing for 'Starkiller' - like an Imperial Knight uniform. And an Imperial Navy uniform. Maybe the Sith Master armour thing from KotOR.
That should do for starters!