UPDATE 2: Some more details have emerged about Thief from GameInformer's cover story.
The game will be primarily played in first-person and will center around a mechanic called Focus. This operates like a "detective mode," highlighting walls you can climb, lights to extinguish and fingerprints that need scrutinising You can also trigger Focus to slow down time while pickpocketing.
As you accumulate Focus you'll gain "attack points" that can be used for emergency escapes. Using one attack point on an enemy's chest will allows you to shove them out of the way, while using more will allow for more debilitating maneuvers.
One of Thief's big selling points will be its AI. "Garrett's enemies understand the topography of the level and which areas could be useful for hiding. Different NPCs will look for Garrett in different ways," noted AI programmer Eric Martel.
Eavesdropping will also play an important role as NPCs will inadvertently fill you in on the details of your environment. One example involved a couple of servers discussing a mishap when the joint's ventilation system was contaminated by opium. Incredulously, Garrett decides this would be a good way to calm a panicked crowd down, so he goes about doing just that. Of course, this means he has to escape quickly while holding his breath so he doesn't accidentally get totally baked (remember: winners don't do drugs).
While Eidos Montreal is remaining cagey on Thief's structure, GameInformer suggested there will be a main hub similar to a mini-open world in which Garrett can take on side-quests between story missions.
Elsewhere, Garrett's tool will include a club, bow, grappling hook, lockpicks, and specialty arrows that can put out flames or expel smoke.
In its basic terms Thief sounds very similar to Dishonored - right down to the mission previewed taking place in a cathouse during an high-class birthday party (which is basically a combination of the two Dishonored levels Arkane was fond of previewing), but then again, Dishonored was heavily inspired by Thief, so we're getting into chicken and egg territory here.
Thief director Nicolas Cantin noted that Dishonored was "more action-oriented" than Thief will be. "There are options for stealth, but they're not really rewarding it," he explained of his competitor. Oli Welsh may disagree with this assessment.
UPDATE 1: As expected, Thief is the subject of Game Informer's next cover reveal.
The images revealed earlier today were lifted from the magazine.
The Eidos Montreal game is simply called Thief, and is due out for PS4, PC and "other next-gen platforms" sometime in 2014.
"Series hero Garrett returns to the Gothic, industrial metropolis known simply as the City to steal any and everything that will make him richer," Game Informer said.
"Unfortunately, the City is broiling with social tension as it is ravaged by a plague and lorded over by a political tyrant known as the Baron. In order to survive his adventures, Garrett will have to pay attention to his environment and make use of the may possible paths through each of the game's levels."
ORIGINAL STORY: Screenshots of Eidos Montreal's next-generation Thief game have leaked.
They may have originated from US mag Game Informer, which is set to reveal a new next-gen game this afternoon.
Four of the images show a first-person perspective, with the player's hands on-screen. The rest are typically sneaky.
The fourth Thief game has been in the works for some time now at the Square Enix-owned developer responsible for Deus Ex: Human Revolution. It is thought to be set for PC, PlayStation 4 and the next Xbox.
More to follow.