Google is wonderful.
I read and loved this 1960's sci-fi book "Simulacron-3", a progenitor of The Matrix, as a boy of 10. All I could remember is that the hero was a namesake: "Doug Hall". But Google found it. The book seems completely out of print now, such a shame. I havn't seen the film "The Thirteenth Floor", which came out in 1999, but from reviews it seems faithful to the book.
Have you seen/read it?
What do you think?
