As the first human Specter – sworn defenders of galactic peace – your mission is to halt the advancing armies of a legendary agent gone rogue. But as you lead your elite team across hostile alien worlds, you will discover the true threat is far greater than anyone imagined.

Three hundred years ago the quarians created the geth, a species of rudimentary AIs, to serve as an efficient source of manual labor. But the geth rebelled against their quarian masters and drove them into exile. Now the quarians wander the galaxy in a flotilla of salvaged ships, secondhand vessels, and recycled technology. Other species tend to look down on the quarians, seeing them as scavengers and condemning them for unleashing a dangerous synthetic life form on the rest of the galaxy.

The krogan are a species of large reptilian bipeds native to the planet Tuchanka, a world known for its harsh environments, scarce resources and overabundance of vicious predators. The krogan managed to not only survive on their unforgiving homeworld, but actually thrived in the extreme conditions. Unfortunately, as krogan society become more technologically advanced so did their weaponry.

Four thousand years ago, at the dawn of the krogan nuclear age, battles to claim the small pockets of territory capable of sustaining life escalated into full scale global war. Weapons of mass destruction were unleashed, transforming Tuchanka into a radioactive wasteland. The krogan themselves were reduced to primitive warring clans struggling to survive a nuclear winter of their own creation… a state that continued until they were discovered by the salarians two thousand years later.

Due to the brutality of their surroundings, natural selection has played a significant role in the evolution of the species. Krogan reproduce and mature at an astonishing rate. Their large shoulder humps store fluids and nutrients, enabling them to survive extended periods without food or water. Their thick hides are virtually impervious to cuts, scrapes or contusions, and they are highly resistant to toxins, radiation and extremes of both heat and cold. Biotic individuals are rare, though those who do possess the talent are typically quite strong in their abilities. But their most amazing physiological features are the multiple instances of major organs; these secondary systems are capable of serving as back-ups in the event of damage to the primary biological structures. This redundancy makes them incredibly difficult to kill or incapacitate in normal combat scenarios.

Roughly 2000 years ago the krogan were a primitive tribal species trapped on a world suffering through a nuclear winter of their own making. They were liberated from this state by the salarians, who “culturally uplifted” the krogan by giving them advanced technology and relocating them to a planet not cursed with lethal levels of radiation, toxins or deadly predators.

But the salarian intervention was not without an ulterior motive. At the time the Citadel was engaged in a prolonged galactic war with the rachni, a race of intelligent space-faring insects. The salarians hoped the krogan would join the Citadel forces as soldiers to stand against an otherwise unstoppable foe. The plan worked to perfection: within two generations the rapidly breeding krogan had the numbers to not only drive the advancing rachni back, but pursue them to their home worlds and eradicate the entire species.

For a brief period the krogan were hailed as the saviors of the galaxy. But without the harsh conditions of Tuchanka to keep their numbers in check, their population exploded. Over crowded and running out of resources on their new home planet, the krogan spread out to forcibly claim other worlds… worlds already inhabited by races loyal to the Citadel.

The so-called Krogan Rebellions continued for nearly three centuries. The krogan sustained massive casualties, but their incredible birth-rate kept their population steadily increasing. Victory seemed inevitable. In desperation, the Council turned to the recently discovered Turian Empire for aid. The turians unleashed the genophage on the krogan home worlds: a terrifying bio-weapon engineered by the salarians. The genophage caused near total infant mortality in the krogan species, with only 1 birth in every 1000 producing live offspring.

No longer able to replenish their numbers, the krogan were forced to accept the turian terms of surrender. For their role in quelling the Krogan Rebellions the turians were rewarded with a seat on the Citadel Council. The krogan, on the other hand, still suffer from the incurable effects of the genophage. Over the last millennium krogan numbers have steadily declined, leaving them a scattered and dying people. Faced with the certainty of their extinction as a species, most krogan have become individualistic and completely self-interested. They typically serve as mercenaries for hire to the highest bidder, though many still resent and despise the Citadel races who condemned them to their tragic fate.

Features :

• Immersive RPG: Determine the fate of mankind as you lead an elite tactical strike force as an epic galaxy-wide conflict unfolds. "Mass Effect" will take the player into new depths of an action-roleplaying game, with choice-based gameplay.
• Rich and engaging storyline. While defending galactic peace and earning a position of respect for humanity in the community, gamers will discover that a greater conflict between organic life and artificial intelligence exists. Players' decisions and actions will serve to shape the destiny of all life in the galaxy as you become absorbed in the story that is "Mass Effect," the first game in an epic trilogy from BioWare. They will become the center of an engrossing story as they battle against alien life forms to save the galaxy from threatening armies.
• Player controls the ultimate fate of the galaxy: The player's decisions and actions will serve to shape the destiny of all life in the galaxy, while raising humanity to the pinnacle of galactic civilization via noble means or via tyranny.
• Real-time squad based combat: "Mass Effect" employs a real-time, squad based, tactical combat system. Players will be immersed in intense, challenging and exciting combat.
• Explore uncharted worlds: In addition to the main story arc of the game, players will be able to visit a large number of uncharted, unexplored planets which are not directly tied to the main story. At any time during the campaign, a player can choose to explore one of these planets in an all-terrain rover in order to discover new alien life, resources, ruined civilizations and powerful technologies.
• Digital actors: "Mass Effect" features a huge cast of in-engine digital actors that you will encounter as NPCs, enemies or as party members. Each will have life-like facial and body movements, and an advanced dialogue system will give them engaging personalities.
• Character customization. Players will be able to choose from a variety of stunning, photo-realistic character appearances at the start of the game, and throughout the game can increase various statistics which will have an impact on their performance during gameplay. Equipment, weapons and armor that are acquired during the course of the story will change the appearance of the characters.
• Next-generation gaming defined. "Mass Effect" takes advantage of Xbox 360's hardware providing gamers with exciting new experiences, including photo-realistic, high definition graphics on an epic scale. As the future of gaming goes online, Xbox360 live features, including premium downloadable content and recognition of achievement will be available via the Xbox Live service.