Supreme Commander 2 takes place 25 years after the events of Supreme Commander . The three opposing sides - the Cybran Nation, the Illuminates and the United Earth Federation - are still fighting in the Infinite War all across the galaxy, spreading chaos and unrest with the player right in the middle as the Supreme Commander.
The game features a single-player campaign where the player takes control of the armies of each faction. The campaign is divided into three parts, each played by a different commander: Commander Dominic "Migraine" Maddox for the UEF, Commander Thalia Kael for the Illuminates, and Commander Ivan Brackman for the Cybran Nation. However, the gameplay remains similar to Total Annihilation , with an insane amount of units on the battlefield at once.
The player can use a variety of units and structures, including the mighty ACU, which can construct buildings faster than normal engineers and has access to powerful weapons. The ACU is vulnerable, however, and if destroyed, the mission or multiplayer match is lost.
The resource management system has been overhauled, requiring the player to have the necessary resources available before building a unit or structure. The resources themselves remain the same, with mass and energy needed to support the war effort.
Each structure can be upgraded with add-ons, such as shields, which increase their defensive abilities. Five tech-trees are available to unlock upgrades for units, buildings, and the ACU, visible on the battlefield with a shimmering aura around upgraded units.
The game features a skirmish mode against AI opponents, with three victory conditions: destruction of the enemy's ACU, complete destruction of all enemies, or the Infinite War. These conditions are also available in multiplayer mode for up to eight players.