I gave this a try. Am I right in understanding that the walkthrough at the moment is basically "ask shamus about ghosts, z, z, z, z, z, z, z, z, south"? EDIT: I actually missed the appearance of the lost spirit until I read the notes. Oh well. (As a sidenote, your .txt files don't have any paragraph breaks. A <i>little</i> annoying to read.)
I thought the game has promise but I do have a few pointers:
Controlling Player's Focus: You draw attention to the writing on the board both in its general description and when you x it, but it's just a random useless detail. If you mention something in the text, you are telling the player it's significant unless you deliberately craft the description to imply it's not. Managing this is one of the fundamental skills of text adventure writing.
To fix this, I'd change the basic description to something like "a board with faded chalk scribbles on it" and emphasize that the writing doesn't matter with something along the lines of "I think that's the board they used to write down stuff during the autopsies? Well, there's nothing legible on it right now. Eh, whatever."
Character descriptions: You have examine descriptions for both Shamus and the lost spirit but they could use some work. Don't describe by listing physical details. It's boring and it doesn't gel into an actual picture. Elmore Leonard recommended leaving out the parts that readers tend to skip and telling the reader the color of their pants or what's their haircut is it.
Instead, give a couple of evocative details that tell the player what the character is
about. Give the player an attitude or use a colorful simile. (x is like y) Try "Shamus is casually leaning against [elaborate code to figure out what he's leaning against in any given room], a ghostly toothpick in his teeth. Cheeky bastard." or "Shamus stands at ease by your side, his squinty eyes taking in everything. The buttons on his uniform shine even through the ghost filter." Adding some detail that hints how old Shamus is as a ghost would be a good idea, as well.
(By the way, did you deliberately pick Shamus because it's an old-timey word for private investigator and would bring up associations with Joey? It would probably be more interesting if you made the ghost companion not a Joey clone. Try a civil war officer or a puritan or a 50s housewife or something.)
Protagonist's personality: There isn't any. I have no idea even what gender the protagonist is or name or if they have any skills or... There are some games where the creator deliberately leaves the protagonist without a gender or personality, but an adventure like this isn't really one where this would work well. You should change the starting textdump a bit to tell the player who you're playing as and make the custom replies to command reveal more about the protag's personality.
Story premise: Ehhhh. Okay, you start the game and then all the ghosts disappear. Now what?
The Blackwell games are ultimately about investigating ghost deaths. If you were making a Need for Speed fangame, you probably wouldn't make it a 3-in-a-row game, right? If I were you, I'd just make a short game in the time frame of the first four games that focuses on the same investigative gameplay.
Tech: I'm actually in the middle of learning Inform 7 with
a book so that I can screw around with prototyping a short adventure or two. If I do, I'll probably cut down the parser to the modern point-and-clickesque examine/use/use item on object, possibly with a keyword parser like
Walker & Silhouette. Frankly, I can do without most of the responses you have to write to make the regular IF parser properly reactive. That's what I'd recommend you do as well.
PS The .exe worked but Gargoyle (which I think is the best multi-platform client at the moment) failed to load the .t3 file. I suspect it's because you used a different library? Dunno.