Defeating the first Boss...
	Speed Runs...
	Unlock weapons...

You can easily defeat the first Boss by ground pounding and shooting at him.

Beating the game once allows you to play through the speed runs (Rianna riding Zeeo to escape from a level) again on your own time.

To get a heavy blaster you must beat Slak Sagar on Alderaan and to get a blaster rifle you must beat Sedriss on Tatooine.