Depending on the choice made in Mass Effect 3, specifically whether the player opts to control the Reapers, destroy them and all synthetic life, or synthesize all organic and synthetic life, the galaxy could change profoundly. The outcome of this decision, however, will not be reflected in the next game.
Speaking to Eurogamer, BioWare studio boss Aaryn Flynn said the fallout of Mass Effect 3's final decision was "acknowledged" in the game's endings.
"I think that's where we want to leave it for now," he added. "We want [Andromeda] to be a new story and it would be very hard to say it's a new story, but also that you need to understand how [the previous trilogy] ended."
The decision to set the game in a new galaxy allows the events of the previous games and the results of a player's action to exist, while also starting a fresh story in the same universe.
Andromeda won't completely ditch the lore the Mass Effect trilogy has established thus far, however.
"It's important for us to have elements from the [original trilogy] for fans to have in the background," said creative director Mac Walters. "Ultimately this is intended to be a fresh story, but we want to have things for people to find and go, 'Oh, I remember that character.'"
He continued: "There's a coalition [of Milky Way races]. We needed to find a way to make sure certain species you're familiar with come along with you on your journey to meet new ones.
"As in the tradition of Mass Effect, there will be certain people working together happily, and certain people working together less happily."
Mass Effect: Andromeda was featured very briefly during EA Play at E3 2016 event. Very little gameplay was shown, and GameSpot asked Flynn about this in a Mass Effect: Andromeda interview following the press conference.
from GameSpot http://www.gamespot.com/articles/mass-effect-3s-ending-wont-impact-andromeda-heres-/1100-6441040/