There's a new 2007 Director's Cut DVD release of the movie in Skandinavia which is approx. 15 min shorter (101min) than the normal cut (115min).
After a less than successful festival and UK theatrical run, the film was recut for its North American release. In the reworked version, the film is ten minutes shorter, the scenes are arranged differently, some scenes are removed, some added, the film ends at a different point, and there are clips of psychologists talking about the ID during the end credits.
The psychoanalysts and philosophers at the end in the pre-credits scene are discussing the "ego" (one's sense of self). Freud's model of the mind has three parts (id, ego, and superego). The ego (named for the Latin word for self) is what Jake Green is up against, also called Mr Gold, also referred in the opening quote as the enemy that hides in the last place you would ever look. In one monologue, there is a recognition that "I'm you (the ego), you're not me." The chess master notes that if you try to destroy him (the ego) to save them (the people around you), they will destroy you to save him (their egos).