Seas of Night

SoN uses a lot of standard Phantasmal stuff like the ConfigD, the
SoulD, the MapD, a fairly standard game driver, and so on.  One of the
most interesting things it does, though, is to set up custom room
types.

   * Custom Room Types *

SoN sets up a path_special object with Phantasmal to make the
GAME_ROOMS_DIR inherit from a different AUTO object than usual.  That
makes every file in that directory inherit from a specific custom room
object, /usr/game/open/lib/cr_auto.  That sets particular kinds of room
behavior for objects in that directory or its subdirectories.

SoN also sets up a custom room binder with MAPD, using
MAPD->set_binding_handler().  This allows SoN to use particular
special kinds of rooms and decide on the fly what room type they're
supposed to be.  That lets the custom rooms be used in standard
Phantasmal room data files, but with custom object types.

Currently, anything that looks like "custom:/dir/roomfile" is mapped
to the file "GAME_ROOMS_DIR/dir/roomfile.c".  That's a nice simple way
to map room names to room objects in the UNQ output files.