I've had my eye on Apprehension for some time, mainly to learn the basics of hammer, as the rundown feel gave the impression that a pre-disaster version would very similar. With Admiral Sakai working on a pre-disaster QE transit station, and that there's actually a lot of inferred story within the maps, I've come to realize that apprehension is probably one of the most important chapters for the entire PD project. As Gordon is kidnapped by two marines, the distance between App. and RP could be theoretically as far as the size of black mesa, so an unofficial route has to be made, unless everyone is fine with two drunk barneys replacing the marines in the PD. (That's called foreshadowing, kids!) Also, one of the biggest things throwing me off track is the doubt of state of repair. "Should this stay how it is, or should i fix it up?"
Most importantly is why, yet it is the thing least cared about.