In 1999 alone, this theme has been explored in "The Matrix", "eXistenZ" and "The Thirteenth Floor." Actually, of the three, this is probably the most intriguing, intelligent and involving, successfully combining the elements of a whodunit with a clever sci-fi tale of a group of characters who drift in and out of a simulated version of Los Angeles in 1937. The plot, though complex, is spun out with coherence and ever-increasing clarity as the layers of information are slowly peeled back to reveal the larger picture. The filmmakers manage to create a sense of unbalance in the audience as we and the characters become more and more unclear as to what is reality and what is a simulation. Because the writers never lose their way, the result is a work of considerable mystery and intrigue.
In terms of art direction and cinematography, the film is a total triumph. The Los Angeles of 1937 the moviemakers have visualized on screen actually has a slight studio backlot, artificial feel to it - perfectly befitting just the kind of world a simulator would create. The photography in these sections also utilizes a slightly off color cast, nicely reflecting the tone found in color pictures of that era.
"The Thirteenth Floor" may not be a very "deep" movie, but it is an honorable addition to a newly formed genre that has not yet had time to ossify in its own conventions. Time alone will tell if filmmakers will be able to expand on this theme or whether, as with most genres, it will fall victim to its own inevitable cliches.