MGS2 is actually the 4th Metal Gear game in the Metal Gear Saga.
THE STORYTELLING
Get ready for some serious notetaking because the prologue of the story is alot to consume. MGS2 begins two years after the Shadow Moses Island (MGS1) incident with Snake and Otacon (now part of an Non-Governmental Organization) looking for the new amphibious anti-Metal Gear that is designed to "wipe the floor" of all Metal Gears being built by many private corporations. Snake's goal was to infiltrate a disguised oil tanker believed to hold this new Metal Gear and confirm its existence by taking photo shots of the new Metal Gear.
Seems straightforward until Russian terrorists attack the ship while several old and new characters appear such as a pregnant soldier, a Russian terrorist leader, and an old revisiting character who's arm is possessing its host. Weird things begin to happen and you'll begin to hear strange dialog (i.e. "la-le-lu-le-lo") in these elaborate cutscenes. When the prologue is done you'll be left with questions into the next chapter. As you progress deeper into the game, more questions begin to pile in your memory banks.
In the succeeding Big Shell Chapter, you find yourself in control of a brand new character, Raiden, supposedly operating under a reformed FOXHOUND two years after the Tanker Chapter. Raiden had a lot of promise but his emo-like personality was his downfall. Fortunately, he sheds most of his insecurities and connects well with characters that support him along the way with strong performances. Although MGS2's story seems to create more questions than answers, you never lose your desire to advance the plot. The story's core stays somewhat intact but in the later chapters things become more convoluted and complex. Perhaps this is Kojima's marketing technique of encouraging players to buy and finish his game to promote discussion. While some parts of the story seems intent in preaching to you proper ethics of politics and power, connecting with his characters are not difficult and the voice performances are strong enough to warrant a continuous playthrough.
When it comes to defending and disposing of bad guys, Metal Gear Solid 2 stays true to its roots.
The Soliton Radar works the same way as it did in MGS1. Moving in 1st person is still a non-existent. Transitioning from crawling to running is still extremely slow as well. Despite this, Metal Gear Solid 2: Sons of Liberty fixes and improves on MGS's shortcomings. Snake and Raiden can now dispose or hide bodies. CQC moves have extended with roll and choke attacks.
While Snake and Raiden may suck at defending themselves, their hiding and recon abilities have improved. They can climb and hang along rails or edges, peer around corners, and put enemies to sleep with their trusty tranq. While some of these changes may seem minor on paper, on screen they work well and emphasize the tactical importance of stealth.
DETAILS
Environments can now work for or against you. In enclosed areas, shooting extinguishers, lights, bottles and other items that can either attract attention or help divert it. You can also squeeze into smaller spaces and lockers. In open areas, Snake can catch a colds, get wet, or bleed which can attract guards from their normal patrol patterns. At first, it may seem annoying but Snake's new stealth mechanics help offset this.
EASTER EGGS
MGS2 contains more easter eggs than all of its predecessors combined. You'll see toy figures from MGS1, taking pictures of hottie posters and getting comments from Otacon. Among some of the most memorable eggs (and easiest to see) is the Codec conversations. Want to listen to Snake's thoughts? Press R1 or R2.
OVERALL
Even after the debut of the Metal Gear series' final game, MGS2 has made itself a big part of the Metal Gear canon and must be played to get the full effect of MGS4's references. The game stands tall even till now. It's hard to find fault in MGS2 but to be fair, there are some sappy moments and the characters can't evoke the emotion. Thankfully it isn't frequent or harmful enough to even matter. It's no doubt that the Metal Gear games will resonate well with their fans as long as Kojima is at the helm. And even if you're not a fan, MGS2 (like most MGS games) ranks as one of the highest echelon of single-player action gaming. It's a game worth playing again after finishing. With a stunningly well-told story, and the gameplay to back it all up MGS2 is a keeper.