UPDATE 21/03 2PM GMT: A Forbes reporter heard more about the issue from a source close to development.
It all boils down to "playable framerate", apparently. "The early builds that the screenshots came from were playable but only just so," the source said. "The game was not in a state where it could be sold at that point. I strongly suspect that they were focusing heavily on delivering a top-notch experience on PC and underestimated the challenges the new systems would pose on PS3 / Xbox360."
"I sincerely don't think they intended to deceive, but in the end they sacrificed a huge amount of graphical fidelity at the very end of development because they couldn't resolve the framerate in any other way."
The footage and trailers From Software used, it did with best intentions, unaware of the sacrifice it would later have to make, the source propositioned.
"The game would have been much worse without the change (as in, many would call it unplayable and broken.)"
Theoretically, such issues could be resolved for a PC version, and Bandai Namco told Forbes we'd hear more about that version in April. The forward-looking engine would also shine on PS4 and Xbox One, From Software told IGN earlier this year, although no next-gen versions of the game have been announced.
ORIGINAL STORY 19/03 1.30PM: From Software has responded to questions about the difference between the version of Dark Souls 2 shown in the world-exclusive gameplay reveal back in April 2013 and the game that came out last week, suggesting that "resource management" during development is to blame for decisions to strip things back.
The reveal footage showed a dramatically lit grey and gold world of rocky medieval splendour, and a castle interior that provided a stark contrast between light sources and shadow. It was an impressive effect.
The retail version, by comparison, looks quite different - particularly the lighting, which is much less saturated and extreme. One comparison video below highlights the discrepancies between the Forest of Fallen Giants section of the original reveal and the respective section of the shipping game, which seems less detailed as well as less vibrantly illuminated.
Some of the changes may be down to shifts in art direction - dialling back the lighting in favour of a more ethereal, overgrown aesthetic - but that can't explain everything. Fans who have been digging into it on NeoGAF have discovered the game was running on a PS3 in the original reveal, too, so what gives?
From Software issued a statement to MCV.
"Throughout the game development process, a game is constantly being balanced not only in game playability, but also in the realm of resource management," a spokesperson explained.
"A developer is always challenged with creating the most rewarding gaming experience while delivering continuity in graphical quality, gameplay dynamics, and balance within the game. The final version of Dark Souls 2 displays the culmination of this delicate balance and we're very proud of the positive media and fan reception for the game."
Dark Souls 2 is hardly the first game to change significantly during the course of development, and the degree to which people are concerned by these changes tends to vary depending on what else they think about the game concerned. Aliens: Colonial Marines was famously less attractive by the time it was released, but the incredibly low quality of that game inevitably influenced the strength of the public reaction. People seemed less bothered by the changes to BioShock Infinite, as captured by our friends at Outside Xbox in the video below.
As for Dark Souls 2, Tom B certainly didn't have a problem with how it looked in our extremely positive Dark Souls 2 review, remarking that much of the game is bright and welcoming despite its hostile reputation. All the same, it will be interesting to see whether the upcoming PC version of Dark Souls 2 regains some of the splendour witnessed in the original reveal.
If you're playing Dark Souls 2, what do you reckon? Do you feel ripped off, do you accept From's explanation, are you happy enough with the game that you don't mind either way? Let us know in the comments.