From what it sounds like, the newest expansion comin out next year is what you are looking for. It sounds like it will be less linear and more open.
Though, there are a few scenarios currently that if the investigators are just wandering aimlessly then they will run out of time before the end.
Ive been looking at that expansion and it sure does look interesting.
Are there any other games that are heavy on the investigation side?
It doesn't matter if its a horror game, any genre will do.