VII & X?

[Ryushikaze]

FFX/-2 and FF7/spinoffs share continuity. This is official, and we know it is official because not only did Nojima say "yes, I wrote 10 and -2 with the concept of continuity of mind", but Nomura and all the other bigwigs have echoed this statement and placed it into the FF7 UOG.

How is not as well known. What we do know is that Shinra, as is revealed in the 'rin did it' ending of the rampaging machina subquest, was interested in the potential of the lifestream, specifically as an energy source. We know from Nojima that after the game, Shinra takes Vegnagun, and attempts to reverse engineer it into a conversion unit (after stripping out its mind, I presume), but fails in doing so. The idea of making an energy unit of this type becomes a massive brainbug of his descendants, so much so that it survives at least two thousand years and an interplanetary colonization in which spirans succesfully migrate to Gaia and (presumably) interbreed with the cetra- which is a logistical nightmare from a genetic standpoint, either requiring an effective miracle, or a separate seed locale for both races, but I digress- In any case, eventually, they finally hit upon this miracle energy source 30 years prior to FF7, and start sucking it up like crazy, since they've slowly become less and less like the innocent Shinra, and more like the President and Rufus. Also, The Sierra is based off technology that Cid excavated, and which is apparently part of what the Spirans brought with them in the move, and lost for whatever (*cough*Jenova*cough*) reason.

I cannot actually tell you anything more than that about the connection, but I can tell you there was a definite attempt to have cinematic similarities between the two, such as the Midgar intro pan and the bevelle dungeons.

Now, I do have some theories about the connection, such as connections between Yu-Yevon and Jenova, and a 'personal druther' with a direct line of descent between Cids. Also a 'druther' descent between Tidus and Cloud, if his unusual circumstances allow him to reproduce (he is technically shinentai, after all).

Anyways, the answers in short
Continuity between 7 and 10?: Yes. 10 leads into 7.
Same planet?: No.
Fully fleshed out?: Not as yet, but Nojima thinks the idea is worth coming back to somewhere along the line.
And no, the ronzo cannot be the ancestors of Nanaki, though it's possible they have a common ancestor on the 'same seed' theory.

Addendum:The only other FFs with a connection as firmly established as 7 and 10 are 5 and its sequel, the OAV legend of the crystals, which takes place 1000 years after and only shares one character in common as a ghost. Also one of the crystals, which takes up residence in one of Lenne's descendant's heiny. I'm not making that up.