Following on from the Ceville demo thread, i thought i would ask what the longest adventure demo was people had played, not in as much as people getting stuck for hours and hours but from the demo's content.
Certainly Ceville would be high on my list

Secret Files: Tunguska. It took me about 2.5 hours to play.

I haven't played many demos other than those for casual games.
But the RealMyst demo was pretty much the entire Stoneship Age.

Besides Ceville I found that The Black Mirror's demo was a fair length. Mind you I had the german demo. I don't play many demo's.
The Art of Murder 2 demo is a good length.

Cathy

The longest adv game demo I recall would have to be for The Longest Journey. It was an entire chapter from the full game, and was very long (and pleasant) to play through.

The longest game demo I played was from an adventure-hybrid game

Indiana Jones and the Infernal Machine. It was an entire level created independent of the full game and took me several hours plus to work through.

I just remembered that the Jack Keane demo was pretty long. 3 chapters out of the game. It took several hours to finish.