It's big but you might be surprised at how much work the programming of the story and the dialogues (if there are any) will be. I'm working on an adventure myself and damn it, I wish clones were legalized!
Cool, what type of game/engine etc. are you using?
You're right about the dialogues - just drew my first NPC and did the dialogue last night. Took a while...
At the moment it's a straight forward converstion where you just read all the text (no clicking different options).
I might do the different options choice but I always thought they were superficial in games because you always get all the dialogue anyway just by going through every option one at a time.
A multithreaded converstions aren't in the budget...which is a meagre 2 euro 50 cent (for coke and crisps)! <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />