SHADE is not a long game. It is not an extensive game in the sense of locations. It has a quite linear course. It is not very difficult, once you get the hang of it. SHADE is simply awesome, just because of the story that is tells.
After a long time, remembering the old text adventures that I played on my old Amstrad machine, I decided to look for something similar nowadays, and I started with SHADE. Now the game is surely much shorter than commercial games were 20 years ago, but the atmosphere was overwhelming. After a while it was easy to find out what to do next, and each action is rewarded with another disturbing reaction of the environment. I felt drawn into the story and could hardly stop until the end, which can be interpreted in various ways. The game takes place in a single location, but the many implementations create a true-to-life experience, even as things start to change.
All in all SHADE is a reference how interactive fiction has to be composed. It is a delightful treat for both beginners and veterans of text-based games.