I eventually got around to playing your game. I would call this a "cute" game - nice graphics and very easy to solve, but it could be so much better with just a little bit of work. Here's some fairly detailed comments for you. I hope you have time to address some of them when you get back from your holidays.
General comments:
When "troll" is used as a common noun, it should be lower case. When "Troll" is used as a proper noun (e.g. "Cave of the Troll" "Trollish dictionary"), it should be capitalised.
Avoid excessive use of exclamation marks. Your game didn't need any of them.
I could hardly examine anything anywhere. (See Adventuron's comments on this.)
There were very few extra verbs catered for. I tried lots and just got the standard "The game does not require the use of the word 'blah'."
Outside Cave of Troll:
"disapointed" should be "disappointed".
EXAMINE TROLL and TALK TROLL are two different things. You should always be able to EXAMINE TROLL, but you can only TALK TROLL if you've read the book. When you TALK TROLL before you read the book, it should tell you "You don't speak Trollish." When you TALK TROLL after reading the book, you get the conversation that you currently get after reading the sign in the corridor.
You can't X TROLL or TALK TROLL until you've read the sign to the treasure room. This isn't logical. What's the sign got to do with anything? You can't read the sign until you've read the book. That makes sense, but you should give a hint when you read the sign before reading the book that "You don't understand Trollish."
SET TIMER: "sunlight, he's looks" should be "sunlight. He looks"; "him. But" should be "him, but".
X TROLL (once he's awake): "TREASURE ROOM?!', the" should be "TREASURE ROOM?' The".
S (with treasure): "treasure! (of course)" should be "treasure, of course."
GIVE TEDDY should work irrespective of whether or not he's given you the key. He only wants to go back to sleep, but don't make it unwinnable. Either let him go back to sleep and drop the teddy in the room so you can get it again OR give some sort of message implying that you should talk to him before giving away the teddy.
End of Cave:
Description says "to your right". This is only true when heading into the cave. It's behind you when leaving the cave. It's better to say "to the east".
Hall of Troll:
"sandles" should be "sandals".
Troll's Library:
"consist" should be "consists".
"book. A" should be "book, a"
The room image is of a book, but when you take the book, the room image is still a book. Perhaps change it to some empty shelves.
X BOOK: "Trollish, it's" should be "Trollish. It's"; "treasure, I" should be "treasure. I"; "reasure" should be "treasure".
Troll's Bedroom:
When you take the teddy, it is still included in the room description. Either remove it from the room description or modify the description with on_describe{}.
Inside Corridor:
"corriador" should be "corridor".
Description says door is to your right, but doesn't say what direction you're facing. In illustrated adventures, graphics are normally facing north, so your image shows the door to the north, which means you must be facing west. It turns out that north is not the door (that exit goes somewhere else) and you are actually facing east and the door is not on your right at all. This is very confusing. You should draw an open exit to the north, say the door is to the east and draw it to the east.
X SIGN: "book, it" should be "book. It"; "TREASURE, it's" should be "TREASURE. It's".
>E
The door is locked! (More unnecessary exclamation marks!)
>UNLOCK DOOR
The game does not require use of the word "unlock". (You must have verbs for LOCK and UNLOCK when you've got a locked object.)
When you come back later with the key, you can go east without unlocking the door. It would be better if you explicitly had to UNLOCK DOOR (check that it's not already unlocked and you've got the key, then set a boolean so that you know it's unlocked), OPEN DOOR (check that it's not already open and it's not locked, then set a flag that it's open), GO EAST (check that the door is open).
Troll's Dining Room:
"Trolls Dinning room" should be "troll's dining room".
Troll's Kitchen:
"kitchen, a" should be "kitchen. A".
"varity" should be "variety".
"counter. Namely" should be "counter, namely".
"windup EGG TIMER" should be "wind-up EGG TIMER."
Egg timer is included in the room description, even after you've taken it. (See teddy above.)
You should be able to SET TIMER anywhere, not just outside the cave. Use a message like "Tick, tick, tick, DING." Use the same message prior to waking the troll. Better still, set a timer using the on_tick{} block and let it count down for (say) three moves, then "The egg timer goes 'DING'."
Troll's Treasure Room:
"room, the" should be "room. The".
"teasure" should be "treasure".
When you take the treasure, it's still shown in the image.