Update: On November 30, 1998, gamers began to learn that being stealthy could be a viable strategy, too—that's because game developers at Looking Glass released the landmark first-person sneaker, Thief: The Dark Project. As writer Richard Moss outlined in his history of first-person shooters, Thief succeeded despite running counter to all the prevailing trends at the time. This happened in large part because "its intelligent enemies—who tried to flee when injured and responded realistically to both auditory and visual cues—opened the door to a wealth of emergent design possibilities." Earlier this year, Ars caught up with Looking Glass founder Paul Neurath to hear about how he and the team developed that groundbreaking AI. And with the game's 20th anniversary happening this weekend, we're resurfacing that interview. The above video and accompanying story first ran on February 20, 2018, and they appear unchanged here.

Older PC gamers who were playing games in the late '90s and early 2000s likely have a soft spot in their hearts for Looking Glass Studios. The company's two best-known properties are Thief and System Shock, though Looking Glass was also responsible for the visually stunning Flight Unlimited and, of course, Ultima Underworld. Although financial troubles at publisher Eidos Interactive (caused in part by the development of the hilarious money pit that was Daikatana) led to the eventual dissolution and sale of Looking Glass, the studio left an outsized footprint on the history of PC gaming through its excellent games.

The Thief series in particular—or at least the first two games—resonated with audiences. The phrase "innovative gameplay" is a laughable cliché in 2018, but Thief really did have innovative gameplay when it was released—other FPS titles had explored stealth-focused gameplay before, but none had managed to so completely capture the experience of sneaking. More, Thief took the unusual (for FPSes at the time) approach of incentivizing the player to not murder everyone and everything in the level—brutality, in fact, was actively punished by the game's scoring system. Sneaking through an entire level without detection became a more important goal than wiping out guards.

But it turns out the tightly coupled gameplay mechanisms that enabled players to so easily understand how hidden they were from the CPU's prying eyes was nowhere near as intuitive to design as it was to use. We sat down with Looking Glass founder Paul Neurath, who was involved heavily in Thief's design and development, to get the scoop. And even though he didn't take any rips from a wolf bong, he did have some juicy info on how Thief and its signature sneaking came to be.