In skirmish and multiplayer play, you start out with an ACU (Armored Command Unit) which is a large, powerful, construction capable unit and your avatar on the battlefield. The single player includes two missions, which were picked these missions to show the more advanced portion of the game. The demo includes two tutorial levels and two campaign levels all played as the UEF faction, but does not include skirmish or multiplayer modes. On February 24, 2010, a demo of Supreme Commander 2 was released on the Steam digital distribution service. Throughout the campaign the player will run into one Commander Gauge, an earlier version of the Proto-Cybrans who is also a bit mad and likes to use a mix of Cybran and Illuminate tech. The end goal is to acquire a planet killer superweapon. Brackman and Elite Commander Dostya, who fights under the direction of his 'father' while attempting to help his friends. The Cybran campaign follows Ivan Brackman, an experimental genetic composite of Dr. The Illuminate campaign follows Commander Thalia Kael as she fights to restore the Illuminate to its former glory before realizing her mistake and turning against her former comrades. The UEF campaign follows Dominic Maddox, a UEF commander who fights off Cybrans, withdraws from the UEF to defend his family and later secures a portal that leads to Seraphim VII. Supreme Commander 2 has 18 missions 6 for the UEF, Cybrans and Aeon Illuminate, collectively.

A trailer for the game released at the Entertainment Software Association's 2009 Electronic Entertainment Expo indicates that the story takes place twenty-five years after the conclusion of Supreme Commander: Forged Alliance, and centers on the breakdown of peaceful relations between the United Earth Federation, the Illuminate, and the Cybran Nation, implying that war has been instigated through a single bullet. The story starts with the newly-elected president's assassination.

Supreme commander 2 uef