We don’t want to create situations where multiplayer players have something that single-player players couldn’t otherwise see.' 'It’s more like a side mission to the single-player. 'They will never be involved in the actual campaign of the main story,' producer Jess Houston said in an interview on the BioWare blog. The characters you play as in the multiplayer side of Mass Effect 3 won't infringe on the single-player story.