I"m playing text adventures for almost 30 years, and when I think "adventures" (OK, OK... "I. F." God...) Fish! is number one on my list. I've played and played and played this game over and over, and I still enjoy it on OSX all these years later.
Magnetic Scrolls really managed to capture the mood of the mid/late 1980s and their games are just a joy to read and play again and again.