Well, with the fail to RP horror, failure to attack the bed, and failure to stay in the room that event happened in, the line of actions I was having my character follow after waking up in the bed was to calmly, quietly, leave the room, find an axe, and end that bed's existence.
I was just doing it slowly, to make it seem like the event was messing with him.
Looking back, I should have been more clear about that. Sorry.
It's fine cheese. Some games just don't work out right. I'm just trying to learn what I can from this one, because I want to run lovecraftian and/or detective stuff that works at some point.
I want to know.
Ok, there's how it works.
Corbitt gets hold of some outsider knowledge. Probably from
Nyarlathotep or something, but it doesn't really matter.
He learns how to transform himself into some sort of undying inhuman form. The tricky part is that this is going to take decades, and he needs to sleep for most of it. So he is literally just lying on the floor in the basement doing his best lich impression. There is a partition wall in the basement with no door in it. He's behind that.
He's been down there for generations. Dozing but aware. He wants his house left alone. If he's worried someone might discover his secret he kills them or drives them off. The optimal result as far as he is concerned is for the house to be shunned as haunted and left empty. So while he lies there awaiting apotheosis he uses his powers toward that end.
He has limited telekinesis, short term mind control (with amnesia for the victim), and the ability to summon a horrible extra-dimensional monster to do his bidding.
He's supposed to be clever and lie low. So arguably he shouldn't have reacted to the players at first, but that would have been a bit boring maybe. So i just had him leap to the conclusion that they were moving in or investigating so he started his process.
First up was some general creepy schtick, he mind controlled Boganski into eating the several months old soup that the last residents had been eating when the mother was taken away to the asylum. But his target was not of a nervous disposition enough to be scared by this weirdness.
The thumping in the bedroom, which was the one he slept in was part of a general strategy of trying to make people believe any 'haunting' was not in the basement.
Attacks on Jackson the magician with the bed and Fortesque the physician with the dagger were successive attempts to produce an injury or death which would interrupt the investigation of the house. But they would be plausible enough as accidents that the authorities would be able to rationalize the weirdness. "Oh your friend just fell through a window did he...that's your story? Are we sure you were not having an argument?"
"Oh dear, this gentleman tripped on the rickety stairs while holding a knife. Most unfortunate tsk tsk tsk." That's what the cops would say.
In the case of the Frenchman it was carefully orchestrated. In order to force him back to the stairs Corbit mind controlled Jones, who was in the kitchen at the time, to remove the fuse for the basement lights again. Jones only noticed a minor discontinuity because he regained consciousness standing in the same room doing nothing in particular.
With the lights out again Fortesque of course headed up with the dagger. It struck him and he fell down the stairs. That one very nearly worked.
The reason the basement stairs are so messed up is because he mind controlled rats and/or humans into sabotaging them and he can make the rickety structure shake with his telekinesis. (The players didn't really meet the rats in the walls. That would have been fun.)
Corbitt himself is formidable with zombie-like durability and a set of claws, but he can't move far or fast. So if the players were pro-active they would have had a shot at taking him out before his Dimensional Shambler arrived and started dragging them screaming into it's hellish home plane.
The Dagger was double edged (har!) if the players broke it he can't summon the shambler to eat them. But it would have done extra damage to Corbitt if you could hold onto it long enough to stab him. An extremely oblique clue to this was available from the father of the last family to live in the house. The power of Corbitt's mind leaked over in the man's dreams, thats why he went mad. But he also knows things. He would have been clutching a Bible and insist on reading to you the section from the life of David where he beheads Goliath with his own sword.
The final confrontation would have been a bit of a meat grinder. Like most short Cthulhu scenarios it follows a Dwarf fortress like philosophy in regard to losing.