The galaxy is trapped in an endless cycle of extinction. Every 50,000 years, an ancient machine race invades the galaxy. With ruthless efficiency, the machines wipe out all advanced organic civilization. They leave behind only the scattered ruins of technology, destroying all evidence of their own existence.Few believe this ancient legend. You, however, know it to be true. The fight to stop this extinction event has become the most important mission in the galaxy."You must act without remorse, without hesitation, and outside the limits of the law."It is your mission. As Commander Shepard of the SS Normandy, you will take your elite recon squad across a galaxy in turmoil, in a desperate race to stop the return of an enemy without mercy. To stop this enemy, you must act without remorse, without hesitation, and outside the limits of the law. Your only imperative is to preserve the safety of civilized life in the galaxy - at any cost. You must become the tip of the spear of humanity, for you alone know the full extent of what is at stake if you should fail.Science-fiction Role-playing: PerfectedMass Effect allows you to create your own customizable version of Commander Shepard (or jump in and use the pre-created character) and plunge yourself into the center of an epic science-fiction story. Choose your squad-mates, your weapons, skills and abilities, and customize your vehicles, armor and appearance - you are in complete control over your experience.In the course of your mission to stop the machine invasion, you may choose to follow the path of the soldier, the tech-specialist, or the biotics-specialisteach of which brings an arsenal of unique yet equally powerful abilities to use against the enemy.