Resident Evil is a series of super popular survival horror games developed by Capcom. The games revolve around biohazards in different locations, involving viruses developed by corrupt corporations. Typically the viruses cause the infected to become zombies, but later installments see them retaining some of their humanity but becoming quite hostile and violent as the series shifts into a more action oriented gameplay.
Resident Evil 0 - Follows Rebecca Chambers, of the infamous S.T.A.R.S Bravo Team, as she investigates a series of murders with her other allies in a seemingly abandoned train. Allying herself with fugitive Billy Coen, she is forced to fight for her life against a horde of horrifying creatures leaked by supposedly diseased Umbrella founder, James Marcus.
Resident Evil 1 - When Bravo team fails to return, S.T.A.R.S Alpha team is sent to investigate. However, they end up discovering one dead pilot and a pack of mutated dogs whom kill one of their own and force the remaining members into a nearby mansion. At Captain Wesker's instruction Chris and Jill investigate the mansion halls allying themselves with Bravo's Rebecca Chambers and their own Barry Burton. The Umbrella Corporations conspiracy is revealed along with Wesker's betrayal, which leads to his apparent demise.
Resident Evil 2 - After the events of RE 1, the surviving S.T.A.R.S team members attempt to educate the civilians of Raccoon City of Umbrella's terrible deeds but it falls onto deaf ears. Soon, an altercation in a secret Umbrella laboratory, involving William Birkin, triggers a massive outbreak of zombies. Leon S. Kennedy, a rookie cop to the RPD and Claire Redfield, Chris' sister, have arrived under different circumstances. The two, along with Ada Wong and William's daughter, Sherry, not only battle the T-Virus but the newly developed G- Virus as well.
Resident Evil 3- Taking place before and after the events of RE 2, the game follows Jill Valentine during her attempt to escape the city. Pairing up with a group of Umbrella hired soldiers and continuously stalked by an unforgiving Tyrant known as NEMESIS who won't stop until all of S.T.A.R.S are dead.
Resident Evil: Code Veronica - The first side story to actually carry significant plot advances. Claire Redfield returns to find her brother Chris, only to discover the existence of the unstable T-Veronica virus. While having to deal with the twins Alfred and Alexia Ashford, Claire and her ally, Steve Burnside, escape to the Antarctic. Chris on the other hand comes in search for Claire and is surprised to discover that his Ex-Captain Wesker somehow survived the events of the mansion.
Resident Evil Survivor - Leon sends an ally of his to Sheena Island to investigate another Umbrella facility. Unfortunately for him he is involved in a helicopter crash and suffers from amnesia. He discovers more of the twisted deeds of Umbrella, one that involves the experimentation of children. Thus he attempts to escape with two siblings: Lott and Lilly Klein.
Resident Evil Survivor 2 - Claire has a dream after escaping the island with Steve, before the second half of the game. It has no plot relevance.
Resident Evil: Gaiden - Barry Burton is sent to find Leon Kennedy who went missing during a mission aboard a cruise ship. When Barry makes it there, the boat is infested with zombies and the only survivor seems to be a young girl named Lucia. In the end it appeared that Leon was the next BOW weapon but the game was pretty much stricken from Canon.
Resident Evil: Dead Aim - A new virus once again surfaces aboard a luxury cruise. Bruce Mcgivern is sent to investigate, wielding a dangerous 'shoot now ask questions later' mentality. The virus is the new T/G Virus and the aim is still the same: Survive.
Resident Evil: Outbreak File#1 + File#2- A group of everyday people are forced into the horrific events of the Raccoon City outbreak.
Resident Evil 4 - Umbrella is finished, bankrupt it appears. The game flashes forwards to the present date and Leon is now a government agent sent to find the presidents missing daughter: Ashley. However, a mysterious new plague that causes the locals to become hostile has infected the once peaceful island and his former allies, Ada Wong and Jack Krauser, appear to be involved.
Resident Evil: Umbrella Chronicles - To fully understand the fall of Umbrella, one must return to the beginning and experience it all over again. This time from the eyes of recurring villain Albert Wesker as he accomplishes his own goals, behind the scenes.
Resident Evil 5 - Years after his former partner, Jill Valentine, was declared dead, BSAA member Chris Redfield, assisted by fellow BSAA member Sheva Alomar, once again face off against his former S.T.A.R.S. Captain, Albert Wesker to prevent an outbreak of the horrific Uroboros.
Resident Evil: DEGENERATION - A warrior seeking revenge unleashes a deadly virus in a Harvardville airport. Responding to the threat are former special forces members Leon S. Kennedy and Claire Redfield, who look to bring down a mutated monster before history repeats itself.
Resident Evil: Darkside Chronicles - Leon S. Kennedy and Jack Krauser's first mission together is depicted, in which the events of Resident Evil 2 and Code Veronica come full circle.
Resident Evil: The Mercenaries 3D - A complete side game with no story elements, depicts several heroes from the franchise battling it out in an action packed game based on the reoccurring Mercenaries mini game.
Resident Evil: Revelations - Before the events of Resident Evil 5, Jill Valentine and her partner, Parker Luciani, search for Chris Redfield and his partner Jessica Sherawat who apparently went missing aboard a cruise ship. However, the new T-Abyss virus has caused yet another biohazard.
Resident Evil: Operation Raccoon City - An alternate universe title, in which a group of mercenaries infiltrate Raccoon City for various reasons. One of which is to kill witnesses, including Leon Kennedy, Claire Redfield and Jill Valentine.
Resident Evil: Damnation - Leon discovers that the East Slavic Republic has been using B.O.W's in a civil war. He encounters a group of rebels who use a strain of Plaga to control Lickers. Meanwhile, Ada Wong involves herself with the Republic's government and their ruthless President.
Resident Evil 6 - President Adam Benford's upcoming speech in Tall Oaks leads to a zombie outbreak similar in scale to Raccoon City. Leon Kennedy, Chris Redfield and Sherry Birkin return with partners Helena Harper, Piers Nivans and Albert Wesker's son, Jake Muller. The three groups are thrust into various biohazards around the globe apparently caused by Ada Wong and Sherry's superior, Derek C. Simmons.
SPOILER RULE
when a new game is being developed/released plot points of the game not revealed in trailers/official releases must be kept under cuts until a month after the games release.That seems like a fair grace period to me.