: Originally, Doom only supported one layer of geometry; e.g. you couldn't
: include the tunnels running under the main chamber in Mars Needs Women. It
: also only had horizontal and not vertical collision detection, so you
: couldn't jump from a high ledge and fly over the head of a player below. I
: don't know whether that's still true in ZDoom.
The second thing you're describing is called "infinitely tall actors" by doomers, and it can be enabled/disabled for vanilla compatibility by ZDoom.
The issue of having object-over-object level geometry may prove bothersome. I could hypothetically use ZDoom 3d floors to accomplish the mars needs women thing, but I really really don't want to make the effort to have to manually write an ACS script to define level geometry. Oy Veh!
For some reason, I seem to remember that the A1 engine couldn't do object-over-object either (something about bridges being impossible to make), so I didn't expect this snag. Meh, gonna need to look at MNW in an editor and see how things are done. Damn if I can't get obed or mapeditorone working though...
