Also, in terms of just walking forward, I understand what you're saying but I would just add for future readers that there's strategy in e.g.:
- timing when to pick up a health
- judging when/where it's safe to explore for items after finding the exit
- using your limited vision to look down corridors and try to avoid getting caught (which sometimes you can't)
So that is where the nonlinearity / decision making comes in, but I get what you're saying :)