It seems like there is a real risk of any given party missing out on a lot of the chapter 3-6 stuff, especially if they only want out (up, to the surface).
Am I missing something or are all these encounters presented as completely optional?
As in, if you want to bring them to Gracklrstugh, and they happen to not just choose it, you'll have to invent your own reason why?
So far, I'm coming up short. Having rockfalls and cave-ins block their way is either incredibly heavy handed, or isn't making them actually change direction.
Having a major location such as Blingdenstone not offer a way up doesn't seem credible.
What are your ideas to keep then in the underdark? What ideas are given to make them actually want to postpone their escape to visit more cities?