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How far along is the next mass effect, I've read some reports saying early stages development and some saying late stages 
Yanick Roy @YanickRRoy
Too late for one, too early for the other... So I guess we're somewhere in the middle? :-)
His estimation seems correct, if we follow this chart

If game development started November 2012 (last DLC by Bioware Montreal), and stretched to 36 month scale (for a fall 2015 release date)
The game is on the verge of exiting pre-production by now, since stuff like mocap, story, dialogue, and gameplay have been in the works. We are about 17 months into the production cycle, which corresponds with where the devs have said about the state of the game. We are about to enter full production, which should last over 13 months!
For further evidence, concept art from N7 Day was released in the preproduction phase (where it should happen), and in December we heard that a section of the game demonstrating most features was operational, which would normally give the green light to enter full prduction 
This makes me more confident about seeing something at E3, I think.