Here are some things you possibly may not have found…
In the forest if you click on the left instead of clicking on the beginning of the path, you will come to a skeleton of some beast. It is also a handy shortcut to the signpost if you enter the forest on accident. You can also find this skeleton by going out of the mine at the forest end, and going back into the forest after you come out of it.
At the signpost if you click on the base of it you will dig up an underground sign with “Hell” on it. There are clues in various places that this sign exists (e.g. “To the parting of five ways”). If you click on this sign you will go down to some huge gates surrounded with Greek and having an ominous keyhole. If you read the Greek you will find that it is not actually Hell, but in fact the Bottomless Pit of Revelation. The listening device in the mine is above it. On the way down to the Pit you can see an unfortunate miner trapped by a cave in, and in the mine you can find the other side of the cave in.
In the Safehame graveyard there is a tomb which you have seen before if you have been eaten by the forest creature. Here in the graveyard if you click at the bottom of the picture you will hear the knocking, and dig up and open a coffin. Out of it steps something like a flightless owl or moth in a greatcoat: an apparent encounter with yourself.
When you go inside the inn you can play the piano. In room IX when you approach the drawers, you can click above them to look behind in the corner, and see a small, shadowy being. If you look out the window after you sleep, you will briefly see something peeking in. Otherwise you would be able to go out of that window, but after you see that you are afraid to, and only want to stay in the room. But if you look in the bottom drawer and see that the crowbar is missing you only want to leave that room.
Inside King’s Krumbs you can click on the mousehole, and it will take you through a secret, tiny place which comes out in the closed up playground behind the School of Thought.
Inside Attanuk & Sons you can look at the desk and use the magnifying glass, and in the back room you can open up the lockers on the right and left. In the Church you can read the booklet and card on the table, and look in the bathtub at the back. These are not quite hidden, but you might miss them.
If you hold the mouse over the hedge when looking down on Baton, you will hear a sinister rustle.
In Neb’s if you click to the right an elephant will appear from behind the clock.
When leaving the island if you click to the right you will find yourself heading into a storm.
If you click on the suit of armor in the tree instead of along the path, you will find a notebook with numbers to call on the telephone. If you have it you can check it again in the phone booth by clicking as if you were going to leave.
If you wait for nine seconds without picking up the phone it will ring, and you will get a call with mysterious, indistinct music, like you may have heard in the mine in the place with the tree roots and the sign pointing up at Auldhame (basically that place is under the “Green Mountain”).
If you dial 911 on the phone you will hear a siren, and subsequently suffer medical malpractice.
If you dial 000000 on the phone you will hear all the sounds from the whole story play at once at a low level until you hang up. I would suggest hanging up soon, and would not recommend dialing this number unless you do not mind getting stuck and perhaps having to close and reopen the tab. Apparently playing all those sounds can make things start to malfunction, and I almost got stuck there once.
If you dial 555342 (the number scratched on the inside of the coffin at the beginning/end) on the phone you can hear the sounds of yourself unburying yourself.
At the top of the “Green Mountain” if you go left you will find a telescope, and five different spots you can click to look at on the countryside below.
In Auldhame you can change the twinkle pattern of the Christmas lights, and depending on which twinkle pattern you have going you can either replay the music-box song (What Child is This), or look at the Christmas card. You can also rustle the presents.
I shall also post something with all the references (that I can remember) that are in the adventure.