Adventure was originally called ADVENT because a filename could only be six characters long in its operating system. The game was renamed Colossal Cave Adventure, as it was based on part of the Mammoth Cave system in Kentucky.
"Crowther had explored the Mammoth Cave in the early 1970s, and created a vector map based on surveys of parts of the real cave, but the text game is a completely separate entity, created during the 1975-76 academic year and featuring fantasy elements such as an axe-throwing dwarf and a magic bridge."
"Crowther's original game consisted of about 700 lines of Fortran code, with about another 700 lines of data, written for BBN's PDP-10. (See the original source code) The program required about 60K words (nearly 300KB) of core memory in order to run, which was a significant amount for PDP-10/KA systems running with only 128K words." (Wikipedia article on Colossal Cave Adventure, accessed 04-14-2009).
"In early 1977, Adventure spread across ARPAnet, and has survived on the Internet to this day. The game has since been ported to many other operating systems, and was included with the floppy-disk distribution of Microsoft's MS-DOS 5.0 OS. The popularity of Adventure led to the wide success of interactive fiction during the late 1970s and the 1980s, when home computers had little, if any, graphics capability. Many elements of the original game have survived into the present, such as the command 'xyzzy', which is now included as an Easter Egg in games such as Minesweeper" (Wikipedia article on Interactive fiction, accessed 04-15-2009).