Joystiq

You can administer morphine to the dreaming Summers, which causes the onscreen Summers to appear in hospital garb, the screen to glow in an ethereal white (with floating blood cells, even), and all the enemies to slow down, making them easier to kill. Maybe the pain alters Violette's perception of events, and the relief brought on by the morphine allows her to remember her successes (since she obviously lived through whatever encounter it was). It is possible to overdose on morphine if you use too much too quickly, which results in an unconscious dream-Violette and an invitation for Nazis to shoot you. This is where the concept gets confusing and a little too meta -- Violette is already unconscious (she's dreaming this, remember), and morphine makes her dream of being unconscious too?
When you get close to an enemy, you can activate a contextual kill-move which plays out in a short cutscene. In the demo, Violette had a knife, so we basically saw her stab people in the back from a few different angles. Replay expects there to be between 50 and 60 kill moves in the final game.

For the most part, Velvet Assassin is like Splinter Cell set in World War II, which is actually more interesting that that somewhat dismissive categorization makes it sound. The demo mission tasked Violette with infiltrating a prison compound to deliver a cyanide capsule to a captured British soldier before any information could be tortured out of him. Violette went from the dank cell block into the opulent warden's office, looking through a secret peephole the warden used to watch the torture, being careful to stay in the shadows the whole time. Real-world-inspired environments like those make the stealth gameplay more interesting.