RomeoJguy doesn't update the often.(doesn't mean he's not working on it) But here's a great video of the mod.
http://www.putfile.com/media.php?n=HydraModVid1
It's a good map, my only problem with it is that you can block the big doors with a physics object.(like a barrel, paint can) It will close and the area will explode, but it won't open again.
You don't have to pay for it, you only need to register. Btw, the mod isn't that good yet.(only deathmatch with stats on their site and some weapon changes) But I'm sure later versions will be tons better. :cheers:
Did you install both CSS and HL2? If not, then you're getting the infamous install error. Just install both and delete the CSS GCF when you're done if you don't want to play CSS. :cat: