As it happens, I’ve recently been playing some Infocom text adventures. Guess what: Infocom were really rather good. Guess what else: there was one rather significant game they never released. And you can play some of it.
In a remarkable find by waxy.org (linked via the magics of QT3), amongst a complete archive of Infocom’s work is the game Milliways: The Restaurant at the End of the Universe, the unreleased sequel to one of the most famous and adored IF games of all time, Adams’ own Hitchhiker’s Guide To The Galaxy. This was discovered on the somehow aquired “complete backup of Infocom’s shared network drive from 1989.”