I dont think any1 really knows that, not until its realised. but what i do know that i can say is its set in the middle east and its set in the future so snakes a lot older this time round, raiden has become a Ninja, and ive also heard this is going 2 be the last in the series and that snake dies in this 1 in the end. i hope so in a way ONLY! because the game has gone on for years and i dont really want them 2 drag it out just 2 make more money off the game.

The story line for MGS4 is thus far the most complex one to date.Snake has aged rapidly due to both his cloned DNA and FOXdie. He is hired by campbell to assassinate the reemerged liquid Ocelot before he can start an inserection by using Naomi Hunter to take control of the nanomachine colony inside Liqids PMC army, SOP(Sons of the Patriots). With this he will have absolute control over the 5 largest PMC armys, an army matching thatof the US. Snake takes on the mission and heads out to the middleeast with the help of the newly formed FOXHound ond the cyborg Raiden.* *Raiden was captured by the patriots while searching for Olga's daughter. They tortured him, yet he escaped and saved Sonny. However the torture has seemed to have forced him into an exoskeloton. His head and spine anr all that remains of his body. Snake enters Liquids battlefield and hunts him down while encounterin old faces(Meryl, Vamp, Raiden)and many more new ones(The Beauty and the Beast Unit, Drebin, Sonny). From there snake is ordered to kill Liquid but is to late to stop him as liquid activates the program to gain absolute control over the PMC's SOP system. At this point not much else is known

IF you remember correctly, at the end of mgs3, when snake kills the boss, he earns the codename, "big boss". He is the real snake. He is cloned into twins, snake and liquid. Liquid transfers his mind and will into ocelot, the agent from mgs3. Meanwhile, major zero has betrayed big boss (original snake) and others out of fear. He creates a system of AI based on past decisions that compiles up data in order to make the best decisions. Snake, the clone, must stop liquid from gaining control of these AI's because they have control over all the weapons' locks and the ability to use those weapons. The story behind the pmc's and the sop's can be read above.

Beats me. And I've completed it twice. Bat shit crazy.

bum bum poo poo you will die snake raiden is awesome and snake needs some botox.

To make long story short in layman's terms, deceased Liquid some how takes over ocelot's body (The right arm has to do something with it) and planning an insurrection to the world and everyone will be controlled and monitored by nanomachines/Liquid. In the other hand Raiden is also on a mission of his own (that's where I think mgs5 is gonna be based on.) En route to insurrect the world, he begins his search for big boss's body which is the only source to get in control of the pmc's (private military companies conducted by the Patriots). Liquid gets cocky and realizes he doesn't need b.b's body and begins a movement called the Guns of the Patriots. This movement is basically a takeover of Outer Haven (warship) and equipping it with Metal Gear Rex's rail gun to make an intimidating nuclear weapon that has the potential to destroy the brain of the pmc -- GW. In the meantime snake is slowly becoming a weapon of mass destruction due to the virus in his body that's mutating and will spread in a period of 3 months. Fast forward, Naomi (Doctor) creates a virus and is completed by Sunny. The virus is called FOXALIVE. This virus is inserted into Haven by Otacon via mk. III. This leads into the malfunction of not only Haven and GW but all pmcs. This event discontinues the Patriots control. Assisting snake in Haven, were the members of Rat Patrol 01... but only Snake managed to get in Haven's system with a little help of Raiden that is, which concludes yet another epic battle of the legendary Hero Solid Snake. P.S. The alleged Big Boss's body wasn't his body after all, instead it was his clone Solidus, which concludes the game with the longest most epic father and son cutscene... Big Boss and Solid Snake! BEST GAME EVER!!!!