Well I think the story begins in the 1940s where a group called the Philosophers (a group of the wealthiest men in USA, Russia and China) poured their great wealth in order to win the WW2. During the chaos in the aftermath of WW2 a member of the philosophers steals all their money. That huge amount is known as the Philosopher's Legacy. During the war, The Boss (then known as The Joy) forms the cobra unit, comprised of soldiers extremely loyal to the boss with superhuman abilities. This unit among other victories helps win the battle of Stalingrad. During D-Day the boss gave birth to the son of another member of the cobra unit, the Sorrow, but was taken away by the philosophers.
Now in the 1950s a soldier named Jack (who would later become The Big Boss) takes part in the korean wars and becomes a student of The Boss.
In the early 1960s, Volgin inherits the Philosopher's Legacy from his father (the guy who stole it). In 1962 the cuban missile crisis takes place. In order to avert disaster the Americans struck a deak with the USSR which included returning the defected rocket scientist Nickolai Sokolov. Also in 1962, The Boss kills The Sorrow (her lover), during a mission in order to save her son. Two years later in 1964 Jack, now a member of a CIA unit named FOX, is sent in a mission to rescue Sokolov. This is named the Virtuous Mission and it is the intro mission on MGS3: Snake Eater. This mission led to disaster as Jack was stoped by The Boss (who appeared to had defected to the USSR). Her new ally Volgin fired a nuclear missile on soviet grounds creating an international incident. Jack was sent in for a second mission called the Snake Eater (which is the main part ob MGS3). His commanding officer is Major Zero (another important figure in MGS lore). His mission was to eliminate the cobra unit including the boss and to destroy the shagohod ( a nuclear armed tank whih sokolov invented). After teaming up with another agent named EVA, Jack succedes in his mission while EVA steals the philosophers legacy for China but that turnes out to be a fake. Half of the legacy is given to CIA by another double agent called ocelot, the son of the boss and the sorrow (who you fight during Operation Snake Eater). Jack is given the title of Big Boss. Another fun trivia is that during Snake Eater you meet Granin a russian weapons scientist who fdeveloped the concept for a bipedal walking tank called "Metal Gear".
1970 - MGS: Portable Ops. Six years after Operation Snake Eater, the FOX unit, led by Gene goes renegade and even captures The Big Boss. The FOX unit siezes a soviet military base in the San Heronymo Peninsula, in south america. With the help of Roy Cambell, Frank Jeager and other red army soldiers he recruited, Big Boss destroyes gene's nuclear missile. Gene left Big Boss with huge amouts of funds. Big boss formes FOXOUND to give the soldiers he recruited a home. Back in the USA Major Zero and Ocelot kill the CIA director and steal the Phiosopher's Legacy. They then create The Patriots, an organization formed to fulfill the Boss' vision of a unified world. Zero then recruits Big Boss, EVA, Signit and Para-medic (the last two were members of FOX that helped you during the last two games. After a while tensions between Big Boss and Zero began to grow. Zero sought to control the world through a single will while Big Boss wanted a world where soldiers weren't used as tools by the government. In 1972 Zero used Big Boss' DNA to create a number of clones. This is known as the Les Enfants Terribles project. Three infants were born: Solid , Liquid and Solidus. In 1974 MGS: Peace Walker takes place in which Big Boss' mercenary group Militaires Sans Fronteres fight the CIA peace sentinel in central america. In 1975 MGS: Ground Zeroes takes place.
1980s - Solidus adopts a young boy named Jack (who will later become Raiden) in Liberia after killing his parents. After finghting in Solidus' small boy unit, Jack would be known as Jack the ripper. After the war Jack disappears. In the late 80s Big Boss founded the indipendent nation of Outer Haven in south africa.
In the 1990s the two first games of the metal gear series take place MG1 and MG2. In 1995 Solid Snake joins FOXHOUND and the Outer Haven uprising begins. Snake's assignment is to infiltrate outeer haven, find gray fox (frank jeager) who had been captured and find out the truth behind metal gear. Snake's commanding officer is Big Boss who leads him through a number of traps. Nevertheless snake survives defeats Big Boss and Metal Gear. Roy Cambell is placed as FOXHOUND's new commander. Snake quits FOXHOUND. In 1999 Zanzibar land becomes a nuclear power and begins to invade it's neighbours. Snake is sent in again and defeats Gray Fox, Big Boss and destroys the new metal gear. In the aftermath grey fox is recovered by foxhound and expiramented on. Big Boss is taken by the patriots and placed in a nanomachine induced coma and Snake seeks solitude in Alaska.
Early 2000s. Zero begins constructing several AIs that would control the world's economy, politics etc and distributes software worldwide to prep for the AIs as a fix to the Y2K bug. Also George Sears aka Solidus Snake becomes the President of the USA. 2005 - The Shadow Moses incident - Metal Gear Solid. A group named Sons of the Big Boss, led by Liquid Snake, take control of a remote facility in shadow moses island and the metal gear rex that was being developed there. Solid Snake infiltrates shadow moses, kills the sons of the big boss and destroys the metal gear. During this mission Snake also meets Meryl (Cambell's Niece) and Hal Emmerich (aka Otacon). Naomi Hunter (sister of Jeager) betrays solid before the mission by planting a virus in him - FOXDIE that kills anyone with Big Boss DNA. Ocelot, who was also involved in the incident, had his hand cut by Gray Fox (now a cyborg ninja). After the incident he puts liquid snakes hand in the place of his old one as a plot to free Big Boss from the patriots. Two years later, in 2007, Snake that now works with Otacon in a group they formed called Philanthropy whose goal is the eradication of Metal gear technology worldwide. This is where the intro of MGS2: Sons of Liberty takes place. Snake infiltrates the USS Discovery in order to tafe photos of the new Metal Gear Ray in development there. Ocelot hijacks Ray destroys the tanked and leaves Snake for dead. Otacon helps Snake fake his death though he is blamed for destroying the tanker. A decontamination facility is built called Big Shell which is actually a cover for Arsenal Gear a submarine fortress which can control the nations army and monitor communications. 2009 - The Big Shell Incident. A group called Sons of Liberty, led by Solidus Snake take control of the Big Shell and kidnap the president. Raiden is sent in as part of the patriot's S3 plan ( to recreate the events of the Shadow Moses Incident and gather data for one of their AIs). Raiden with the help of Snake, Otacon, Otacon's sister Emma (who worked there) and Olga Gurlukovich (as a cyborg ninja) defeats the sons of liberty, solidus and plants a virus in GW that cripled it. Ocelot, now seemingly being controled by liquid escapes with a metal gear ray and arsenal gear crashes in manhattan. The patriots manage to extract the s3 data from GW.
2010s - The world is now in turmoil. Wars are spreading everywhere through private military companies - PMCs. The whole economy of the world is based on the constant fighting. The SOP system in enforced which allows governments to control all soldiers engaged in action. All PMCs are controled by ocelot/liquid through his company outer haven. In 2014 MGS4: Guns of the Patriots takes place. Cambell recruits Snake to assassinate liquid. After chasing him through the middle east and south america, Snake finally catches up to him in eastern europe. He also meets up with a lot of familiar charachters: Meryl, Raiden, Naomi and EVA. Liquid captures the body of Solidus (thinking it is Big Boss) and takes control of the SOP system. Snake infiltrates shadow moses to stop liquid from taking the rail gun. Snake finally infiltrates outer haven and uploads a virus which crumbles the SOP system along with whatever control the AIs had but leaving the energy and resource networks intace which are essencial to modern soiety. Snake finally defeats ocelot/liquid. By destroying the AIs Big Boss awakens and meets up with Snake for the final time before he dies. Along MGS4 Naomi, EVA, Ocelot all die.
I tried to write all the important events in the series but I skipped a lot of important details and characters
