Well, a couple of things should make sense from what the previous posters mentioned about certain achievements, but here's what can be missable, just 2 though. (Or maybe more if you choose in different paths.)
"Terrifying Assassin" (Since you can just escape from him, but wont get you the achievement) and "What are they Worth". (If you don't feel like getting all the caps though in 1 play.)
Last edited by The Stray; 07-15-2011 at 07:48 PM.