Classic Interactive Fiction
Colossal Cave Adventure (also known as ADVENT or Adventure) is one of the earliest computer adventure games. The original (referred to here as Advent 350 after the maximum number of scorable points) was written by Will Crowther in the mid 1970's and later expanded substantially by Don Woods. Many later versions have been produced including the others listed here.
Inform Games
Inform is an interactive fiction design language created by Graham Nelson in 1993.
Infocom Games
Infocom was a software company founded in the late 1970's by several MIT students and graduates. It created the first commercially successful text adventures, starting with the seminal Zork series which marked the beginning of a golden period for interactive fiction.
Note: For most Infocom games listed (Enchanter onwards) you need to provide an original story file. To do this click on the "Select a Story file" button just below the game map at the bottom of the game page. That will bring up a file chooser dialog where you can locate your story file (if you don't own the story file for the game, you can't play it on this site, sorry).