In development at BioWare Montreal
BioWare Montreal studio director Yanick Roy has shared some information on the next Mass Effect game which he says "will be very respectful of the heritage built over the course of the first three games" and built with the Frostbite 2 engine used for Battlefield 3.
Roy continues: "... we are exploring new directions, both on the gameplay and story fronts. You can still expect the pillars the franchise is known for to be fully intact though, including diverse alien races, a huge galaxy to explore, and of course rich, cinematic storytelling."
The studio worked on cinematics, N7 missions, and much of the downloadable content for Mass Effect 2, in addition to handling multiplayer and the upcoming Omega add-on for Mass Effect 3, among other things. BioWare Montreal will be supported by the team in Edmonton "through the game's development," according to Roy.