"The whole idea of Mass Effect3 is resolving all of the biggest questions, about the Protheons and the Reapers, and being in the driver's seat to end the galaxy and all of these big plot lines, to decide what civilizations are going to live or die: All of these things are answered in Mass Effect 3."

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It's more like there are some really obvious things that are different and then lots and lots of smaller things, lots of things about who lives and who dies, civilizations that rose and fell, all the way down to individual characters. That becomes the state of where you left your galaxy. The endings have a lot more sophistication and variety in them.

— Casey Hudson