This page attempts to clarify the criteria used on Chrysalis to select the games we cover. On the surface it might seem an easy matter, but read on below and you could find out that the issue has more complexity than you'd think if not familiar with the issue.
Final Fantasy Series
Quite naturally for a Final Fantasy wiki, every game title with canonically (and currently) 'Final Fantasy' in the title is covered. This includes the main (numbered) series, sequels and prequels to the main series, and the various spinoff series and titles.
'Final Fantasy Legend'
What was known as 'Final Fantasy Legend' to early US players is actually a series known as SaGa. It was marketed to US players in a ploy to get them to play an unfamiliar title. The SaGa series doesn't have anything to do with the Final Fantasy series, and thus isn't covered on Chrysalis.
'Final Fantasy Adventure'
What was known as 'Final Fantasy Adventure' to early US players is more correctly known as a series called Mana (聖剣伝説 [seiken densetsu] in Japanese). It started out as a title called Seiken Densetsu: Final Fantasy Gaiden ('legend of the holy sword: a Final Fantasy side story'), and the only thing it had in common with the FF series was the inclusion of chocobos and moogles. Unlike what the US marketing team of the time would have you believe, all Final Fantasy elements were dropped from the series by the second title, and remakes of the first game have removed all FF elements from even that.
The conclusion is clear. The Mana series is not the Final Fantasy series, and the two have nothing to do with each other save a marketing ploy in the series's first installment. The Mana series isn't covered on Chrysalis.
Final Fantasy Mystic Quest, also known as 'Final Fantasy USA: Mystic Quest' and 'Mystic Quest Legend', is a title developed for the US market at a time when RPGs were not popular outside of Japan. Most (if not all) of its features (including graphics) were taken from Saga 3. Of the 'Final Fantasy' titles released in the US in the 90s, this was the only one that was actually a Final Fantasy..to a degree. There was nothing but the name in the series to connect it to the Final Fantasy series.
While based on the name, this title could be covered on Chrysalis, there remains the problem of its contents. This decision may be reversed if a good enough reason to do so comes along, but for now Mystic Quest isn't covered on the site. It simply doesn't have anything in common with the series.
Vagrant Story is the oldest non-FF title covered on Chrysalis. While the title doesn't canonically include 'Final Fantasy', it is heavily hinted right in the game that it takes place in the FF world of Ivalice. Further integration of VS into the FF series has been done in later FF titles, which reference back to VS itself. This leaves no choice but to cover the game, as it is clear that you cannot get a complete picture of the world of Ivalice without it.
The Chocobo Series
Back in the 90s, the chocobo proved very popular among players, and thus a spinoff series was created around it. These spinoff titles revolve around playable chocobos in various worlds where chocobos can talk, wear clothing, and have jobs. There are also several racing game titles centered around chocobos, and other spinoffs of the spinoff series. The whimsical nature of the games makes it clear that they aren't set in the same universe as Final Fantasy titles.
While chocobos are indeed quintessentially Final Fantasy, this spinoff series is completely different in mood and execution, and doesn't contribute any lore to actual Final Fantasies. It isn't covered on the site.
The famous crossover between Disney worlds and Final Fantasy worlds, as well as a completely original framework to it all…is in contrary to the expectations of some, quite easy to differentiate from Final Fantasies. The developers have made it clear that these aren't the 'real' Final Fantasy characters traipsing about the Disney worlds (like the case is with the Dissidia spinoff series), but instead a universe of its own entirely. For this reason, there is nothing the KH series could contribute to Final Fantasy lore.
The Kingdom Hearts series isn't Final Fantasy, and thus isn't covered on the site.
The Bravely Series
Once again we have on our hands a seeming Final Fantasy title, but one that does not actually have 'Final Fantasy' in its title. The game started out development as a sequel or continuation to 4 Heroes of Light, and was made largely by the same team. It includes traditional FF jobs, abilities, items and world settings. Indeed, the only things missing are moogles and chocobos, and those are not present in every Final Fantasy game either. The inclusion of Final Fantasy is to such a degree that the game feels more familiar to old FF players than 4HL, since the latter included many differences from the norm.
For now, a compromise has been made. The main titles of the Bravely Series are covered on Chrysalis, as there is no difference from FFs with them despite the lack of series name. However, Chrysalis staff is small and can barely keep up with the confirmed FF series, so minor titles in the series (such as social games) are not covered beyond a brief introduction.
There have been quite a few titles that include cameos from Final Fantasy characters. The series is, after all, very popular and has existed for several decades already. Do note, however, that a cameo or two (or even a few dozen) from FF characters does not a Final Fantasy game make. These games with cameos are not covered on Chrysalis.