The game was well-received, shipping over 7 million copies worldwide and scoring an average Metacritic aggregate score of 96%, making it the fourth highest-rated game on the PlayStation 2, and the tied sixth highest-rated game of all time. While the gameplay was universally acclaimed, critics were divided on the philosophical nature and execution of the game's storyline, which explores themes such as memes, social engineering, political conspiracies, censorship, and artificial intelligence. It has been considered the first example of a postmodern video game, and has been cited as a primary example of artistic expression in video games. The game was controversial due to its complex narrative and unconventional protagonist.