Eidos Montreal narrates 10 minutes of live Thief gameplay on PS4 in this video from E3 2013.
Game producer Stephane Roy explains what's going on as it happens, and shed a little more light in a Q&A following the presentation.
The demo takes place a few hours into the game, when master thief Garrett has taken it upon himself to steal a Heart of the Lion gem from the unpopular Baron ruling the city. He has to infiltrate the Baron's vast mansion as an angry mob approaches. Guards swarm at every turn.
Throughout the course of the dark demo we see the shadow mechanic (icon in bottom-left of screen) put to good use as Garrett snuffs out braziers with water arrows. He walks more softly on grass than he does on water and this dictates his route, though he's up high before long.
Garrett pounces on a guard and shoots another in the head but generally prefers to leave most untouched. Roy pointed out in the post-demo interview that while Garrett's combat abilities can be improved, he will never be an out-and-out fighter capable of striding into hostile areas unhidden.
Garrett shooting one guard in the head highlighted a new Focus feature he has. This can increase aiming ability, allow you to see the route forward, highlight interactive objects and even allow you to steal multiple things from people in the blink of an eye.
Focus is an exhaustible luxury so you'll need to pick your moments. It sounded like you can replenish it by finding some kind of flower as you sneak around, but I'm not certain.
The rope arrow was demonstrated, the pickpocket timers evident and we got a glimpse of the dogs that will hamper your skulking with their much keener senses than the oafs apparently controlling them.
Stephane Roy explained after the demo that by tilting the PS4 pad you can activate Garrett's Swoop dash ability. It's a small tilt and he was very enthusiastic about it. He also said the studio was experimenting with blowing on the bundled PS4 headset microphone to have Garrett blow out candles. But there's fine tuning to be done to ensure this is a useful mechanic rather than a quickly forgotten gimmick.
Thief will have a directed story experience but it will also have city hubs that you can move around outside of those missions where you can take on side-quests, Roy said.
Thief is in development for PC, PS4 and Xbox One. It's due next year.
The video is below. Gameplay starts at around four minutes and ends at 14.