The story of Gun Metal revolves around a futuristic world where an evil force threatens humanity's very existence. The player takes on the role of a "Havoc Suit", a high-tech combat vehicle that can transform into two different forms: Mech and Jet Fighter. Equipped with a range of deadly weapons, the player must embark on various missions to defend against the enemy's aggression.
The gameplay in Gun Metal is fast-paced and action-packed, as the player navigates through levels, completing objectives and fighting against enemy forces. The game features a variety of missions, including defending bases, escorting convoys, and attacking enemy strongholds. With its emphasis on speed and agility, Gun Metal challenges players to think quickly and react fast.