Mass Effect 2 is the sequel to BioWares hit space-based 

role-playing game (RPG), Mass Effect. A single player adventure

Mass Effect 2 allows players to continue the adventures of the

fully customizable series hero Commander Shepard, as you take on

a whole new adventure and a new cast of supporting characters. 

Additional new features include the ability to import game save

files from the original Mass Effect game to continue the

adventure in an unbroken fashion, a new damage system,
a new, more flexible dialogue game mechanic and more.