The Metal Slug series begins with the story of Donald Morden, a former soldier who becomes corrupted and seeks revenge against the government and military after the death of his son. He forms the Rebel Army and wages war against the Regular Army. The Regular Army recruits two of its best soldiers, Marco and Tarma, to take down the Rebel Army and put an end to Morden's plans.
However, Morden escapes and forms an alliance with the Martians, who have their own plans to take over the Earth. The Martians use the Rebel Army to weaken the Regular Army, and then plan to destroy both armies and take over the Earth.
The heroes of the game, including Marco, Tarma, and new recruits Eri and Fio, must band together to stop the Martians and save the Earth. Along the way, they discover that the Martians are creating clones of the heroes to use as soldiers.
The story concludes with the heroes defeating the Martian leader, Rootmars, and saving the Earth. However, the series continues with more games and storylines, including the introduction of new characters and villains.
Here are the key facts extracted from the text:
1. The story of Metal Slug begins with the Regular Army, an organization that combats terrorism and world chaos.
2. The Regular Army is led by Donald Morden, a tough and efficient leader who has a son.
3. In 2023, a bombing occurs in which Donald's son loses his life.
4. Donald becomes depressed and turns to alcohol, but his hatred for the Regular Army helps him rise and dedicate his life to destroying those responsible for his son's death.
5. Donald creates the Rebel Army, with the goal of putting an end to the Regular Army and the corruption that exists between the government and the military.
6. In 2028, the Rebel Army launches attacks against the Regular Army.
7. The Regular Army recruits the best scientists to create a weapon to resist the threat of the Rebel Army.
8. The scientists develop a super vehicle called the Metal Slug.
9. The Rebel Army, led by Donald Morden, discovers the existence of the Metal Slug and begins an operation to capture all the prototypes.
10. The Regular Army contacts two of its best elements, Marco Rossi and Tarma Roving, to recover the Metal Slug and put an end to the Rebel Army's plans.
11. Marco and Tarma prove to be effective against the Rebel Army and destroy many of their tanks.
12. The Rebel Army is led by Donald Morden, who has a plan to take over the world.
13. The Regular Army and the Rebel Army join forces to fight against the Martians, who are trying to conquer the Earth.
14. The Martians are led by Ruth Marx, who has a plan to destroy the Earth and take over the world.
15. The heroes of the story, including Marco, Tarma, Eric, and Cold, join forces to defeat the Martians and save the Earth.
16. The story of Metal Slug 2 involves the Martians trying to kidnap the heroes and clone them to create an army of super-soldiers.
17. The heroes of Metal Slug 2 join forces with the Regular Army and the Rebel Army to defeat the Martians and save the Earth.
18. The story of Metal Slug 3 involves the heroes fighting against the Martians and their leader, Ruth Marx.
19. The heroes of Metal Slug 3 defeat Ruth Marx and save the Earth.
20. The story of Metal Slug ends with the heroes saving the Earth and the Regular Army and the Rebel Army joining forces to maintain peace and order.