After the success of the first MGS game, demand for a sequel was big. The first game set high expectations for following titles, and the development team set out to make the most of the Playstation 2's capabilities in regards to graphics, gameplay and rendering capabilities.
A demo for MGS2 was released alongside Zone of the Enders, another Konami game that used the same engine as MGS2. It showed a lot of what was to come with the full game, and its inclusion as a demo disc drove sales up for Zone of the Enders, with some people even buying the game just to play the MGS2 demo! Eventually stores that offered video game renting, such as Blockbusters in the US, started offering the demo by itself for renting.
The game had it's highly anticipated release on November 12th 2001. It was supposed to be released earlier, but due to the 9/11 attacks it had to be pushed back to change some of the games contents.

The game is split into two parts, called the 'Tanker' and 'Plant' chapters. The Tanker Chapter follows Solid Snake as he infiltrates an oil tanker in the Hudson River to take photos of a brand-new Metal Gear rumored to be developed there. The name of this tanker is The USS Discovery, the same name as the submarine Snake is on when he first enters Shadow Moses in the first game. He is joined by Otacon, who gives him support over the codec. We learn that since the events of MGS1, the two have started an anti-Metal Gear organization by the name of Philanthropy.

Everything seems to be going well, until the tanker is taken over by a group of Russian mercenaries led by a man named Sergei Gurlukovich. Snake has an encounter with the mans daughter, Olga Gurlukovich. This fight serves as the first boss of the game. We also learn that Olga is pregnant, but refuses to leave the tanker despite her father's wishes.
After Snakes battle with Olga he makes his way into the hold where RAY, the new Metal Gear being developed by the Marines, is being kept. Snake photographs RAY and sends the pictures to Otacon, who plans to post them online and expose the Marines activities.

Like before, everything seems to be going according to plan. That is, until the surprise appearance of one of Snake's old foes from the Shadow Moses incident, none other than Revolver Ocelot. Ocelot escapes with Metal Gear RAY and destroys the tanker. It sinks, taking the legendary Solid Snake down with it.
This is how the Tanker Chapter ends, with Snake seemingly drowning in the Hudson River, and the sound of Otacon yelling his name through the codec...

We skip forward two years, to the same place where Snake was last seen. A familiar voice, namely that of Colonel Campbell, recounts the sinking of the tanker two years ago. He tells you that the event let out large amounts of oil into the river, and that a cleanup facility called Big Shell was installed in order to deal with the aftermath. Though now, the facility has been siezed by a terrorist group calling themselves the Sons of Liberty. We learn that the group has taken several hostages including the US president James Johnson, demanding 30 billion dollars. And if they do not have their demands met, they plan to destroy the Big Shell and create the worst environmental disaster in history.

Who's the Colonel talking to? Snake, of course! But...his voice sounds nothing like before. And is that blonde hair poking out from under his mask?
That's right, as you might be able to guess, this is not the Solid Snake we know. In fact, he won't even keep the codename, as it's switched to Raiden almost as soon as he enters the facility. He's a rookie on his first mission with his only prior experience being VR training, and he will serve as the protagonist that the player controls for the rest of the game. This bait-and-switch is the first of many twists and turns the game will throw at us, and you'll soon find out that things are much different than how they appear on the surface...