Hands on:
http://www.gamespot.com/xbox360/acti...w_6133348.html
"The ruined city through which Dom and Marcus are making their way is beset by Gears of War's malevolent alien antagonists, the locust horde. The locusts apparently thrive in the shadows, so the soldiers have to stick to well-lit areas or risk being ripped asunder by whatever lurks in the darkness.
In one instance, we fired on an old car to set it on fire and then pushed it down a hill, essentially creating a mobile light source that we could run behind. But the car didn't stay ablaze for long. Oops. Later on in the demo, we got to turn a valve to let loose a stream of flammable liquid down a path, and we then had to shoot the stream to set it on fire, creating yet another path to continue on."