Adventure games, especially
text-based ones, are often known by fans as `
interactive fiction'. The first
text adventure was
ADVENT, also known as `
Colossal Caves', by
Will Crowther and
Don Woods. The physical layout of
rooms in ADVENT is based very loosely on the
Mammoth and
Flint Ridge Cave system in
Kentucky; Crowther is a
spelunker who participated in the exploration of that
cave system.
Probably the most popular series of adventure games is the Zork series, which contains both text adventures (Zork I-III, etc.) and graphical adventures (Zork: Grand Inquisitor, etc). Infocom, the company that released Zork commerically, went on to release a wide variety of other text adventures before eventually going under and being bought by Activision.
Nowadays, there are a number of people writing text-based (and other) interactive fiction which is even better than the old Infocom games. They populate rec.arts.int-fiction. Examples of recent (post-1993) IF that is very good: Jigsaw, Lethe Flow Phoenix, A Change in the Weather, For a Change, Tapestry, and Photopia; the last two are more fiction than interactive, as they have very little in the way of puzzles.
While modern graphical adventure games often have rather linear plots, this is not true for all of the genre. I offer the original Maniac Mansion as a shining example of a good nonlinear game---you can win in a number of different ways, depending on which members you choose for your party. Similarly, Jigsaw is rather nonlinear---while there are a few dependencies among the time periods, they are the exception rather than the rule.
For more information on the new wave of text-based interactive fiction, read rec.games.int-fiction and rec.arts.int-fiction, and perhaps visit ftp://ftp.gmd.de/if-archive/ .