In 2010, BioWare Montreal was developing a competitive, multiplayer first-person shooter called Mass Effect Team Assault, but it was reshaped into the third-person co-op mode that shipped in Mass Effect 3, according to a Kotaku report based on the iPad app The Final Hours of Mass Effect 3.

Mass Effect Team Assault saw four months of production before being presented to the Mass Effect hierarchy and transforming into Mass Effect 3's multiplayer skirmish mode.