Game file used by Interactive Fiction (IF) interpreters, such as Spatterlight or Zoom; contains a Glulx story in Blorb format, which is a format used to bundle different game resource files into a single archive; different resource files include music, graphics, and level information.

GBLORB files are similar to .BLORB files but are used for only Glulx games. A GBLORB file is an .ULX file contained in a Blorb wrapper, which gives it more capabilities, like storing resource files. .ZBLORB files, which are similar to GBLORB files as well, are used by Z-machines.