At E3 this year, THQ showed an impressive, if somewhat unrepresentative, demo of Metro: First Light. Instead of showing the game as it will play, they created an all-action sequence that shows off quite how remarkable the engine is. Rather than offering slow, spooky the atmosphere you'll really be playing in. The first part of that video, broken up into three chunks for maximum annoyance, is below.
The trailer shows off how you can manipulate the environment to your advantage, bringing darkness to areas infected by light.