Well here are my thoughts on the subject of if the quest is too hard:
For me, it seems very difficult, but to me all this is kind of new and that adds to the difficulty. I come in and take over a pure fighter type character, which I like playing and would like to continue to play, but in reading the back posts and now in this new encounter; he seems to not be of much use most of the times.
There have been riddles, traps, and puzzles; all of which are great but a pure fighter who doesn’t have any abilities beyond fighting isn’t much help there. Most of the escapes from these traps seem magical; again not much help from my character.
Then along comes a fight; and my weapons and armor are not much good and cant damage the opponents. Though, it seems the magic isn’t much help either so that evens the playing field among characters.
You say the solution is simple, that clues have been given; I have read back quite a ways and I can’t figure it out. Now I will be the first to admit I am no brain, but the simple solution eludes me. I have never sat and played table top games before so I don’t know if this type of ‘thinking’ adventure is common; but if it is, it seems to be very difficult and sometimes frustrating when everything you think of to try doesn’t work or backfires.
Now I don’t mean to criticize your DMing in any way; your presentation of the story is great. But the solutions of these puzzles seem to make it difficult and I will admit does take some of the fun out of it. It just seems to me that one, after the other, after the other, just tends to slow things down so much that the excitement fades. In reading back posts I saw areas I was glad I wasn’t playing at the time as it seemed so slow; and coming in at a battle I thought this was some excitement, but to face a foe that defeats your best easily while taking no damage on their own sure puts a damper on the case.
I hope you don’t take this hard; I just believe in being honest and telling you my thoughts. It doesn’t mean the adventures have to be easy; but we are big damn heroes right? Oh wait wrong game. But if the difficulties seem insurmountable and after trying the players can’t seem to solve the riddle, perhaps someone should assist them a little. Maybe one of the NPC in the group could slip a ‘hint’ out to guide them in the right direction. Or the DM could slip a PM to a player and say “Hey you suddenly remembered this from awhile back.” I guess you could roll for that and let it decide if they get a hint and who gets it. I still am not sure what you roll for exactly other than combat.
To sum up; the game is great, and definitely challenging, but if things seem to stall and people aren’t getting it, maybe throw a fresh hint their way in some fashion to move things along again.
I am not an expert in table top games, but I did sleep at a Holiday Inn Express once.