Is that it?
If you want some good feedback on this please give me more detail. What is this story that you mentioned? What changes are you making to the Fallout system? When you say "system" are you talking about mechanics, interface, or game play?
Just make sure to expand your topic if you want good feedback.
While I was reading your post I was thinking of Metal Gear Solid and was happy that someone already mentioned it. The idea, as interesting as it is, is a real nuisance to play through. As much as I would like to state all the fun things about this idea, I will focus on the bad. That's all that matters when giving feedback anyways hahaha!
The first problem that I find with this concept is the all-mighty 4th wall. When I play a game, I want to be submerged into it; especially in MMOs, I want to become my character. However, when hazards affect the player, it's like a slap back to reality. Second, punishing the player might not be very "fun" for them.
So if you plan on doing this, you really have to make sure that you aren't punishing the players too much.
Right now you have an interesting idea, a concept. It would be nice if you update your first post and expend it a bit. Give details. For example, do I have to complete a dungeon for each ingredient? Or do I find all the ingredients that are needed to make one potion in one dungeon? Also you call the book "Potion Brewing - Basics", does this mean that the book can be upgraded or new books can be found? What kind of game could this be implemented in?
I definitely agree that potion making as been a bore in the past; even Minecraft made the process of making a potion a bit tedious (They don't give you a recipe book!) However, your idea sounds fun so make sure to expand it.
Sounds good, but make sure that each level introduces something new to it. This could be a new mechanic, enemy etc.
For example, my favorite random dungeon game is Final Fantasy Fables: Chocobo's Dungeon. I love it because it brings many things to the table. New themes, enemies, classes, abilities, power ups, and hazards as the dungeons progress.
So, if your mind is set on the 20 stages, they really have to be set apart from each other.
Don't think that first person increases the fear factor. Dead Space and Alan Wake are wonderful examples of how a third person can still be scary. If you do go the first person pov rout then you would be competing with games such as Left4Dead and Dead Island (Yikes!)
This all depends on your game, but I feel like there is more of a connection to the character in 3rd person, because you get to see them.