TIE Construction Facility
Starkiller is a young man in the second level, which takes place in an Imperial TIE Fighter factory that is under attack by the Rebels. You will fight several Rebel militia troops and an AT-ST. The level's boss is Rebel General Rahm Kota, who becomes a major character later in the story.
Jedi Temple
Starkiller then arrives at a heavily guarded Jedi Temple to prove his loyalty to Vader. You will encounter resistance both outside the Temple and within from Stormtroopers and Imperial guards. The boss of this level is a Sith Lord named Darth Desolus, who was once a Jedi.
Raxus Prime
Raxus Prime is a junk planet; you will face several different robots here. The level's mini-bosses include Junk Behemoths and a mercenary named Drexl. During the boss battle, you must first defeat the Junk Titan, which then serves as the mech-body for the second boss, Kazdan Paratus.
Jedi Temple 2
Starkiller returns to the Jedi Temple to face more Stormtroopers and Imperial guards. The boss here is a Sith Lord named Darth Phobos, who is difficult to beat. She has a tendency to disappear, reappear, clone herself and give Starkiller vertigo, which is represented by a slow-moving camera and hallucinogenic-style trails when battling.
Felucia
The alien jungle of Felucia is a dangerous place for Starkiller. You will encounter Felucian warriors and exploding gaseous plants. The mini-bosses in this level are several Rancors (Jabba's beast from Return of the Jedi). The level boss is a Jedi Master named Shaak Ti, who will call for help from the Felucian warriors.
Nar Shaddaa
There is a brief cutscene that takes place on Vader's flagship, and you are then thrown into space by Vader. Afterwards, you'll travel to Nar Shaddaa looking for a blind drunkard named Rahm Kota, whom you defeated in level two. The level boss is an Imperial Shadow Guard, who calls on the aid of Shadow Stormtroopers.
Jedi Temple 3
Starkiller, under Vader's orders, must begin building a Rebel alliance to overthrow the Empire. You'll return to the deserted Jedi Temple again. There are a few jetpack-wearing Stormtroopers here. After you deal with them, you will fight the boss, the rogue Jedi. You find out in the following cutscene that he is Starkiller's father.
Kashyyyk
You head back to Kashyyyk to save Princess Leia Organa from the Empire. Starkiller battles Stormtroopers, Jetpack Stormtroopers and Wookiees. The two mini-bosses are both AT-STs, and the level boss is a difficult AT-KT. It is commanded by Ozzik Sturn and is guarded by a force field that must be dismantled before dealing with the machine.
Dark Felucia
When you return to Felucia in search of Senator Bail Organa, you will battle Stormtroopers, Rebels, Felucian warriors and Felucian snipers. The mini-boss is a difficult Bull Rancor. For the boss battle, you must defeat Shaak Ti's padawan, Maris Brood.
Raxus Prime 2
You head back to Raxus Prime to destroy an Imperial shipyard to get the Emperor's attention. You will face all kinds of Imperial troops. The mini-boss is an AT-ST, and the level boss is a difficult Shadow Guard aided by Shadow Stormtroopers.
Cloud City
Starkiller heads to Cloud City to meet with Senator Garm Bel Iblis. Here, you must defeat the Mandalorian bounty hunters and survive a mini-boss battle with a thug named Kleef. The boss battle is a long one. You must defeat more Mandalorians, a Basilisk War Droid and then the Basilisk's owner, a Mandalorian named Chop'aa Notimo.
Death Star
A cutscene places you and several senators on Corellia, where a treaty to fight the Empire is being signed. Vader double-crosses Starkiller and appears with Stormtroopers to arrest everyone. Starkiller vows to avenge this betrayal and heads to the Death Star. Here, he must defeat dozens of Stormtroopers, disable tractor beams and defeat an AT-ST in a mini-boss battle. You must then fight Darth Vader twice and defeat the Emperor to save the Alliance members.