Adventure was the very first text adventure of all time. It inspired the genre and its name.
The point of the game is to gather a variety of treasures and bring them back to a small building. The game is pretty accurately based on the Mammoth Caves, which explains the mazes and the fact that exits and entrances sometimes don't match up exactly (i.e. going west and then east may not leave you where you started).
For me, the most enjoyable way to play this game was to keep it at a slow pace, going back to it time and again while playing other games. I kept a numbered list of every room with all of its exits to other rooms. This made the game much easier. After several weeks, I got to a point where I couldn't get any further for several days. I finally looked up a walkthrough for the last three or four puzzles.
Once you get all the treasures, there is an endgame that is surprisingly good; it seems more like a modern deconstruction of the game than the very first game of all.
I played the 350 point version, and I found the game incredibly enjoyable. I admit that I used the wicker cage bug (as mentioned in another review), where you can carry everything in the wicker cage. To get full points, you must remove the items from the cage outside of the building before placing them in there.
Every Interactive Fiction player should play this game because so many other games reference it heavily.