Having taken a few trips to rivervale myself I figured something very...very odd was happening there. From the halflings who were simply sitting by the water, seemingly mesmerized by the undoubtably dangerous lights in the water, to the very fact that this was the only city I found to be pretty much open only at night. Having not explored the zone myself much I can only draw upon the information that has been graciously provided by others. So to that end...
What we know about the vale
1) The scarecrow => Strong as hell apparently, well....maybe not strong...but definitely pretty healthy. Perhaps the scarecrow does present some key. Could it be possible that the scarecrow is a manifestation of the life forces of the accumulated once living halflings? Possibly would account for his truly insane amount of health. I'm also assuming that this individual does not talk, as it has never been my privelige to even view him, as I was rather cautious to aquiesce to the demands of the halflings to not wander from the path, thus my explorations were ultimately limited.
2) The mistlights=> They remind me of what little I've seen (Thank all the gods) of the mist tendrils. My contact with these has also been limited with the exception of an ill fated exploration of the elven home in lesser faydark. If they are not as powerful as these others (and they seem not to be from the accounts above.) are they similar in nature and or composition? They could even be the souls of the halflings in the city now that such occurs to me. Do the numbers of the mistlights and halflings match up?
3) The crops...how many are there? One would assume if they were to have the power to free the former living citizens of rivervale from their torment, there would be enough of them present to do so.
4) The halflings... they are friendly as aari said and I myself experienced. Though there are a number of questions inherent in their existance that may help to shed some light on the nature of the mists themselves. Perhaps a greater exposition at length of what we know of the history of rivervale would shed some light (though hopefully not enough to cause it's residents to despawn) on the topic. There are a number of things that I find odd however, even considering the hypothesis that they are in fact undead...
A) They despawn during the day, at least most of them do... I do believe I've seen some during the daytime, but I could be mistaken, as memory is truly a fickle entity. Few undead that I have seen do this. There are the mummified froglocks of miel that do, as well as the tomb king. But many do not, including the mummies in northern tarrhyl, the denizens of freeport, the entities in kaladim, the undead residents of first ruins, the iksar skeletons near elvenhome, murdered guardsmen on the way to kingspass, and the dwarven skeletons in goblinskull to name a few. Whether this indicates an oddity in the existance of these creatures that do not appear in the daytime or some property of the undead created in the wake of the mists is unknown to me.
Perhaps given the nature of the undead discussed extremely powerful undead retain a certain intolerance to the daylight hours, as most of those mentioned that appear during the daytime are not powerful. Then of course there is the underlying trend that skeletal beings such as the residents of freeport seem to be unaffected by the daylight hours. The spectres in kaladim may be simply unaffected as it is constantly dark there, whether day or night. Also if I recall correctly was not kaladim attacked before rivervale? As some have suggested the mists may be weaker the further they spread, growing thinner. Thus the halflings may be unaffected to the extent of the denizens of kaladim, though both apparently seem to attempt living normal lives from my limited observations, even to the extent of having shopkeepers, bars etc. The citizens of freeport also provide ample evidence of this phenomenon, although I theorize this may simply represent the dead being unwilling or unable to accept the nature of their new existance. Being unable or unwilling to move on, they simply cannot cope, and so cling to the remnants of what they once did. It would be truly interesting to determine whether an enchanter could convince the undead in freeport and kaladim if they were one of their own, and go among them to learn what they could, although it may be too much to hope that any fruitful conclusions could come of this.
B) They seem friendly but become very very upset when one travels from the path.. however they still warn people from straying from it. This in it's very simple nature presents a difficult problem. Do they realize somewhere, perhaps on a basal level, their true nature? They may be attempting to warn individuals as to save them from the fate they will be forced to visit upon them, much the same as a certain scavenger gnoll I had the interesting experience of encountering whilst wandering the badlands. This said they seem to not have lost their underlying human, or halfling I should say natures. Whereas other undead most certainly have (freeport who attack on sight, or kaladim residents who do much the same). Regardless a number of possible hypotheses present themselves
1) They really really want to hide something off the paths, whether they are being forced to, or want to.
2) They have limited control over their natures. This control only extends to the "path" areas and they realize this.
Experiments to try
1) To further determine the nature of rivervale's residents invisibility may provide some clues. Should they be able to see through regular invisibility, the particular variant to ward against the sight of undead should be tried. Conclusions here are obvious.
2) Talk to the scarecrow? Perhaps some phrase or question will provide further information from him?
aari brings an interesting thought to mind...The mistlights may simply be the combination of the souls of the halflings and the mists. Perhaps the mists, being weaker in that area for whatever reason, were unable to sustain themselves in the prime for whatever reason without this extra "help". Thus they bound themselves, accounting for the listless halflings complaining of warmth. As for why others of their kind do not display this behavior who knows... perhaps not all of the souls were neccesary to sustain the mist? Or it could simply be the force of the victim's will that keeps it from endlessly staring at the lights.
But then again I digress as usual. I will undertake further exploration of this area in the future and see what I can discover and I am sure others will do so as well.
