I also join those who do not believe Mr Greul was the cat killer.

I believe Morgan threw Jemima in the fire after some sort of conflict with Greul.

I think I should point out that not all Saxton residents cheer Nigel on on his search for the crown. Except for the ghosts that provide the actual clues, most of the townspeople expressed misgivings if not outright hostility towards the crown being found and removed.

I clearly remember Nanny Noah tell Nigel that things that are lost sometimes should remain that way, Lucy argue against him that it was not his to take and Professor Oogle also discouraging Nigel from searching for it, though he seems to have a change of heart during the fair.

I noticed the tears but thought them a visual clue that something is wrong with the time, and never noticed the discoloration other describe after the crown is found . Now that it has been mentioned though (hi Ivinia, nik2008ofs from JAF here ), I really like the idea of Saxton being a computer-generated reconstruction using old photos, though it doesn't explain everything. Surely such a virtual world could and would smooth certain discrepancies over automatically, like the date on the package Hadden sends to Nigel, who himself thinks he lives in our time?

Btw, I thought that the whole cast being around the tomb in ghostly form before Nigel returns the crown meant that the power behind it (Grindel? the old kings? perhaps even Hadden?) somehow held their spirits/souls/consciousness/whatever captive, and that was the reason they didn't recognize Nigel, not simple refusal to acknowledge him out of anger or disappointment. And the fact that Lucy finally breaks the silence and helps is because Nigel tells her, and through her the power behind the mess that he wants to return the crown.

Hadden Industries found a way to access the spiritual world using computer generated virtual worlds. Then one of 2 possibilities – they send someone in as an experiment to see what happens, or they know about the Lost Crown, and want to find it for themselves.
I believe that Nigel, Lucy, Alex and possibly a few others (Morgan, Professor Oogle and Rys) are contempory people. Nigel and Lucy work for Hadden and are friends (hence the pictures of them) . Nigel is sent into the virtual computer world of Saxton as an avatar, and is given a new life history (1978, stole documents, being persued). Saxton is virtual world based on information that Hadden gets from Hardacre. Prior to Nigel going into Saxton, they sent in Hardacre as the first experiment. I think he dies in the process. That’s why he appears in the game as both an avatar and a spirit.
Saxton is populated by both spirits and avatars of people made up by Hadden, possible based on people they used to get information to create Saxton in the first place. The non-spirit avatars – Alex, Morgan, etc.- have preprogrammed behavior. Only Nigel ( and Lucy to some extent on an off and on basis) is able to change events, and act independently
While Nigel is in Saxton, he communes with the spirit world. He also develops the desire to find the Lost Crown for himself. While interacting with the spirits, he is able to help a few, thus sending them to rest. Some he cannot help – Rose and Bob’s grief over their lost son, Gruel’s dementia from losing Jemima. He also encounters evil spirits, the Agers. As he exposes their crimes, their evil influence disappears. When he actually has the Lost Crown in his possession, he has a dream of what happened to Hardacre when he had the Lost Crown. That dream becomes a virtual reality the next day. Because of the attitude of the inhabitants and his belief that the power of the Crown protects Saxton (perhaps even being the power source that allows he spirits to roam), he has second thoughts. Hadden then wants to pull him back using Lucy. Perhaps they want Nigel to bring out the Crown, or they feel Nigel’s life was in danger like Hardacre’s.
Nigel goes back to return the Crown, and is supported in his endeavor by Saxton’s residents. He is returned to the present successfully.

who was the ghost in the crypt that kept throwing stones at Nigel even after all the other ghosts had been exorcised? He seemed to be a very tortured soul - mark the way he appears in contrast to other ghosts; this one seems to be in pain while the others stand still for most of the time. I still haven't figured out who that might have been.

some people Nigel meets are ghosts - the couple at Ager House, for example, or Nanny Noah. I thought that was quite obvious; however, I was a little puzzled by Hardacre - in the first night, he seems to fade while on the next day, he can't remember a thing about having talked to Nigel. This, of course, would be evidence for there being different time shifts - makes sense to me.

the black mist. I know Nigel exorcised at least three of the Agers - what about the fourth one? Which one or what manifested himself/itself as that black mist? I can't figure that one out.

the painting of the crow tree in the musuem? I thought it was really important since both Nigel and Prof. Oogle talked about it, hinting that there might be some clues hidden in the painting. But then I never got to go back to the painting, it just slipped from the game...