There are four SNK fighting game series with (mostly) mutually canonical timelines:
Parallel universes with many similarities to these that happen not to fall very strictly within this timeline include the KOF series, the Samurai Shodown series, and Buriki One. It should be noted that KOF and SS have some timing problems within their own timelines, though (due to the spinoffs and multiple retcons).
The four series covered here are consistent enough that an incomplete timeline can be made.
The Last Blade series takes place in the Japanese bakumatsu period, a sort of cold war that was de jure a conflict between supporters of the shōgun and the Emperor, and de facto very complex in its issues and allegiances, but in its time would have been difficult to recognize as a strict civil war (and still would be so, even with today’s historical hindsight). It precedes the Boshin War (1868–9), which established a modern, Western-style régime under the rule of the Emperor of Japan.
The other three series ‘emigrate’ the story out of Japan (in actuality, the Last Blade series was released after most of the games in the other three), and into and around a fictional city (actually, two cities; the original was destroyed) in the United States with some of the more ancient conflicts immigrating along with the descendants of the Last Blade characters. Some of the Fatal Fury games are worldwide in focus, however.
Southtown, USA is a very cosmopolitan city with eclectic influences from real-life cities all over the United States. Unlike most U.S. cities, however, Southtown has a permanently entrenched tradition of organized crime, street brawling, and frequent global crises stemming therewith (ironically, the character of the organized crime seems to have reduced the amount of gang activity and drug abuse in the city). Particularly considering the general unrest levels in America from 1964 to the early 90’s, the 20th-century crime rate is not really overexaggerated; the more futuristic settings are a continuation of the mob influence that in actuality ceased its more public activities in the 1980’s due to hard-hitting U.S. government action and the rise of street gangs.
Its geography and atmosphere probably aligns best with SoCal cities (and many games strongly hint that it is close to the border with Mexico), with the notable exception that the sea is to the south (which is probably the origin of the name); its grittier nooks look more like those of Chicago or New York (as depicted in films, of course), and its architecture, like many U.S. cities, is highly eclectic (you can catch glimpses of American Gothic, Spanish missions, and of course lots of the typical post-Bauhaus glass/steel/concrete constructions). The ethnic profile of the city is probably too diverse to estimate accurately from the games, but there are very prominent Asian populations (particularly from Japan, Korea, and all parts of China) and descendants thereof, many of whom still have strong ties to their countries of origin.
The “King of Fighters” tournament in Fatal Fury was continued in the “spin-off” King of Fighters series, which actually has its own timeline and events (the primary conflict with the timeline on this page is that the Art of Fighting characters would have to be a whole generation younger to make their concurrent appearances with the Fatal Fury characters; moreover, characters in KOF do not really age over the years). To add to the complexity, KOF has its own spin-offs, creating multiple canons; the string of local-ish KOF tournaments in the style of the Fatal Fury series is continued in (what will eventually be) many KOF spin-off games, whereas a cataclysmic international KOF tournament with the highly formal invitations and dire consequences worldwide is chronicled in the main KOF series. Moreover, this being long after the end of the NEO·GEO era, SNK now owns the properties of many of its former second-party developers, and some of these factors are also imported into the modern games, which would add very much to the confusion if KOF were included on this timeine. However, the events on this timeline more or less cease with anything released by SNK Playmore (i.e., post-bankruptcy SNK) so far, with maybe a couple of exceptions (because some KOF elements are required to time the events). Perhaps they will expand on it soon enough (I hope they do, someday!).
The Samurai Shodown series does not truly tie in to this timeline in anything more than tangential ways (e.g., Shiranui Gen'an being a distant predecessor to Mai), and Buriki One was a one-off, so they can be excluded without truly losing important details, or introducing highly contradictory ones.
Finally, it should be noted that within the Fatal Fury series, the events of Fatal Fury Special, Real Bout Fatal Fury Special, and Real Bout Fatal Fury 2 (even if there were any to mention) are not canonical. They are dream match games. If Real Bout Fatal Fury Special: Dominated Mind could be said to be canonical, it would have taken place in 1998.
This timeline is a harmony of two sources, all research credit going to them:
First, we connect Last Blade with Art of Fighting 2.
Zantetsu is predecessor of the AoF Kisaragi Eiji (though it seems that they are not related by blood). Not only do they both bear a frightening grudge about proving that their school is the strongest, they use the same moves. Because Eiji himself is depicted in Zantetsu’s ending, the evidence is strong enough to link the series.
The connection between Art of Fighting and Fatal Fury is easier to understand.
The setting is clearly the same Southtown (with the map in AoF2 and FF having the same layout, and Geese Tower located in the same place), and Geese Howard makes his appearance in Art of Fighting 2 as a boss.
Moreover, Mark of the Wolves makes it quite clear from Marco Rodriguez’ story that Ryō is the leader of Kyokugen-Ryū karate.
The problematic connection is Fatal Fury to Fūun; it should be there, but the evidence is flaky.
This much is known: The old man Zhong has the hat given him by the “legendary wolf” (Terry), and does the same hat-throwing celebration; and the relative/descendant of the Taegwondo master Gim Gap-hwan, Gim Su-il.
However, Zhong’s hat is blue, and Terry’s is red; also, Terry supposedly bequeathed his hat to Rock. While these facts are not wholly contradictory, things have to be stretched quite a bit for both of these to be true.
Because the Fūun series is supposed to take place at the beginning of the 21st century, it should be sometime around or after the events of Mark of the Wolves. Since the world setting is clearly somewhat different between the two, one can conjecture that either Fūun actually takes place a pretty good time after Mark of the Wolves (I’d estimate 2020–50 would be fair enough), or that Fūun has been split off to be a parallel universe (which is more likely).
In the story, Last Blade 2 should take place half a year after the events of Last Blade, but everyone’s age increased by a year [this is only a minor problem].
The dates being the latter weeks of June to the beginning of July derive from the (real) Ikedaya incident taking place 8 July 1864. In Washidzuka Keiichirō’s ending in Last Blade, we are told that of the Shinsengumi that “Rōshi are gathering at Ikedaya and Shikokuya”, so Last Blade had to take effect before the incident. In addition to that, at the beginning of the ending, Washidzuka mutters (probably of Kagami) that “he was a dreadful guy....”, implying that it couldn’t have been long since then. Therefore, the listed end date must surely be early July in 1864. However, there is still the possibility that Washidzuka was referring to some other fight, perhaps a long time before.
The first Last Blade has mostly autumn and winter stages, and Last Blade 2 has mostly spring and summer scenery. If that is the case, just when did Last Blade take place? It doesn’t seem very plausible that autumn happens around January to March [even less so with the first few months of the lunar calendar, it being shifted forward if you want to include Ikedaya]. You could try to make the case to keep the autumn in 1864, but in this case, you have to date it after Ikedaya.
A plausible fanon-style dating would ignore the official dates, and set the beginning of Last Blade in late 1863, assume (reasonably) that the fights can be up to a few months between each other allowing time for everyone’s journeys, and that Kagami is defeated in the early months of 1864; about half a year later (around between ’64 and ’65) the Shijin begin the search for the Maiden of Sealing, and Kōryū and Setsuna appear, and after Kōryū is defeated, the Jigoku-Mon may be sealed. This takes more than half a year between the end of LB and the beginning of LB2, but it solves the discrepancy while throwing out a minimum of official facts, and allows everyone to age a year [especially if we cheat and use the older Asian system of incrementing one’s age on New Years instead of birthdays].
Official materials state that Rock was 7 years of age when his mother Mary died and he went to Terry. In the same materials, it is said that Geese died a year later. Therefore, Geese should have died when Rock was 8, and Rock would participate in Maximum Mayhem 10 years later (making him 18). The problem is, Rock is 17 in Mark of the Wolves.
This page makes it out so that Rock is introduced at the time of Fatal Fury 3, and Geese dies in RBFF a year later, Rock is found by Terry when he is only 6. If we assume this, his mother dies when he is 6, so he then goes to Terry; at the age of 7, his father dies, and he fights with Terry; and so he participates in Maximum Mayhem at the age of 17.