welcome to the universe of Metal Slug. The year is 20XX and the whole world is at war. Factions such as The Regular Army, Rebel Army and the Ptolemaic Army are at war. Even aliens such as Martians and Invaders are a part of this war. Choose your Faction

The Regular Army: They are the military arm of the Earth Federation transitional government. You will be a part of their special units either its the P.F Squad led by Major Marco Rossi or S.P.A.R.R.O.W.S

The Rebel Army: The Rebellion Army was born out of and as a consequence of multiple terrorist groups that began to emerge in the opening of the 21st century. Led by General Morden, they seek to remove the Regular Army and take control of the world as they believe that only they can protect it. You will be a part of their unit that either being; Ace Command led by the cunning Abigail, The Frozen Brigade led by cruel and cold, Beatriz, Blaze Brigade led by Grazia, and Allen Platoon led by the fearsome Allen O'Neil

The Ptolemaic Army: A terrorist organization with advanced technology with two sub-division that being the cultists or the Main Army. You can be either the cultists, where you will follow Mira's orders, or the main army of the Ptolemaic where you will be led by Commander Dragunov.

Martian Army: Led by the giant Rootmars, they are extremely intelligent beings that seek to save earth from humanity. You can be either a human or a Mars People yourself. Due to Rootmars returning to Mars to recover, you will be following The Professor

Invaders: They are ferocious insect-like beings with shapeshifting aspects. They are also able to assimilate powers and traits of the creatures they feast on, thus increasing the power of their swarm-like army. Their main goal is to assimilate all of the universe into their empire.

Independent: You can choose the other faction such as, Amadeus Syndicate or The Mummy Army. Or you can be your own character who serve no higher power