I don't know if as_oilrig would ever really work as a hostage rescue or
bomb defuse map, without some major changes to limit some routes.
The map has way too much connectivity. As a Terrorist, you can
spawn and in about 6 seconds you can be in or right next to the CT
spawn (if you take either vent routes). If you're intent on
adopting the map for CS or DE, I would definitely remove the vent
routes.
With that being said, I don't think as_oilrig would work well as a
hostage rescue map. No matter where you put the hostages the CT's
are going to have to lead them pretty far. I think the de_
scenario would work better.
Assuming you'll keep the T's spawning on top of the buildings by the
chopper, and the CT's spawning in the small room with the ladder and
vent, then I would put a bomb site next to the water pit and one on the
first floor of the elevator room. Obviously, you should add some
oildrums or extraction machinary to bomb to make it believable.
As for porting it... if you feel comfortable enough remaking the map
from scratch, you can give it a shot. It's unlikely you'll be
able to maintain the original dimensions, but this may work out since
you'll probably have to do some serious fiddling with the layout.
If you don't want to build it from scratch, I'd first decompile the
original (using the map decompiler found here:
http://www.snarkpit.net/editing.php?page=files&game=HL&type=utilities)
and then port the brushwork to source. You can learn how to port
from HL1 to Source by reading this thread:
http://forums.fortress-forever.com/viewtopic.php?t=497&sid=7f1e08cab2bd4d197e465e44791dde3c
I'm not exactly sure how the community feels about decompiling and
porting and editing... I personally don't really have a problem
with it if you're attempting to "Source" an old map.
To be honest, I think you're probably better off creating an entirely
new version of the map. Keep the setting, and the emphasis on
Z-axis battles, but come up with some new routes and geometry. I
feel that if you're too faithful to the original the map won't come out
as well.
Well, anyway you cut it as_oilrig definitely has a lot of untapped
potential (as either a source of inspiration or the subject of a direct
port) and could be made to look spectacular for Source.
MoneyShot, I hope that helps.