Speaking at Gamescom, BioWare said that it believed Mass Effect 3 was the perfect entry point to the series thanks to the refinement of all the game systems, and the balance between action game and RPG.
The company compared its series to Star Wars, noting that the "first" movie that was released in that series was actually the fourth episode, and that the later-released prequels added background story that wasn't essential to appreciate A New Hope. Mass Effect 3, they argue, is the same -- the "invasion of Earth" story stands alone, but having played Mass Effect 1? and 2 will provide players with more in the way of context.
And there will be plenty of context -- BioWare promises that it will resolve the consequences of each and every decision that players have made throughout the course of the whole series. The team is very keen on what it calls its "emotional storytelling" approach, where the consequences of Shepard's actions and decisions aren't necessarily immediately clear -- but they have a profound emotional impact when they do. During the demo, an example was shown: while exploring, Shepard came across a young boy in an air vent. Shepard reached out and tried to help the boy, who ran away. Much later, Shepard saw the same boy boarding an evacuation craft as the Normandy lifted off from the fallen Earth -- an evacuation craft which was quickly destroyed by the invading Reapers.
Mass Effect 3 is out next March, releasing simultaneously on Xbox 360, PC and PS3 for the first time in the series' history.