Do not read any further unless you're really frustrated!
Okay, you asked for it!
The solution to the game can be fully given by a description of what each item does. So, here's a list of all important items, what they do and where they are.
sword - located under bridge. Used for cutting down thorns in the road and for knocking an old dead branch out of the old tree.
key - located inside the old oak tree. To get it, operate the branch. Used for opening a door in the obelisk.
stick - knocked out of the old tree with the sword. Used to get silver cross out of the swamp.
silver cross - located in the swamp. Used late in the game to drive the spectre away. Note: the spectre does not go away for good, you must wear the cross every time you enter that room!
shield - located in the front hall of the castle. Dip it in the cauldron to turn it into silver, then wield it to get up the stairs behind the tapestry.
book - located in the study. Gives a hint for later. See spear
garlic - located in the kitchen. Repells vampire in the same way as the spectre. Note: you must be wielding it for it to work, just like the cross!
scroll - gives the hint for the shield.
spear, rag, and match - located in the armory, the laboratory, and the kitchen closet, respectively. Used together to make a fiery spear, which can then be thrown at the spider web.
bag of powder - located in the laboratory. Used late in the game to keep the wizard from blasting you into ash.
gold ring - located in the spider web. Used to protect you from the basilisk's gaze. Must be worn to work.
crowbar - located in vampire's room. Used to pry up a board from the kitchen closet floor, and to destroy the machine.
board - see crowbar. Used to make a bridge over the pit.
winged boots - located in the tower. Lets you walk out the tower window if you're wearing them.