Players of the original Mass Effect had a big impact on the story of the second, if they imported their character save from the first game. BioWare imported some 700 player choices and associated plot points into Mass Effect 2.
BioWare lead cinematic designer Armando Troisi said during today's Mass Effect 2 Game Developers Conference session that it was "the small things" that mattered when carrying over player data from the original Xbox 360 and PC sci-fi role-playing game.
Troisi illustrated this to the development crowd by showcasing a scene from Mass Effect 2 set near a holographic kiosk that played a trailer for a movie based on the events of the original Mass Effect. This particular plot hook involved two choices, one based on Commander Shepard's gender, the other based on a late game choice involving the Council. That meant four Mass Effect 2 design choices impacted by the first game.
With the third game in the Mass Effect trilogy supporting the same save file transfer system, BioWare has their work cut out for them if they plan on supporting another 700 plot points.