A Z-Machine interpreter/development library (source files)
fizmo_source-0.8.5-1-source
Fizmo allows you to play interactive fiction, also known as textadventures, which were implemented either by Infocom or created using the Inform compiler in a terminal.
You can also develop your own interactive fiction front end in C or any C-related language like C++ or Objective-C.
You'll find a huge number of adventures at http://ifarchive.org and http://ifdb.tads.org/