Menacing from the first scenes onward, Star Wars: The Force Unleashed is set in the period between Star Wars episodes III and IV. You play as an apprentice to mean old Darth Vader named Galen, a.k.a. "Starkiller."
The old bat tells you it's your destiny to execute Storm Troopers and rebels, because they get in the way of murdering the good Jedis in the universe. So you kill masses of them with your light saber.
This is a fun campaign to watch and wage, mostly, and the game play is intuitive. You easily learn to swing a saber and unleash magical "force" powers. As the game proceeds, you acquire new forces and fight moves. The occasional cinematic scenes are conventional, but pretty and effective. Yet at its heart, this is a standard sword-type action-adventure.
The only serious problem is you can't challenge other gamers in any multiplayer level online or offline, on the PS 3 and Xbox 360. The Wii will let you play multiplayer offline; the PSP and DS, online. That limits the shelf life of the game in my house to 20 hours or so, instead of hundreds of hours online.