How Thief's Stealth System Almost Didn't Work | War Stories | Ars Technica 1998's Thief: The Dark Project was a pioneer for the stealth genre, utilizing light and shadow as essential gameplay mechanics. The very thing that Thief became so well-known for was also the game's biggest development hurdle. Looking Glass Studios founder Paul Neurath recounts the difficulties creating Thief: The Dark Project, and how its AI systems had to be completely rewritten years into development.