At Eurogamer Expo, Valve announced some details about Left 4 Dead 2's Realism mode. It isn't a different difficulty setting but rather an additional gameplay tweak that can be used with the four existing difficulties.

"With this, we remove the glows, we make events like the Witch more important now, because if the Witch hits you once, she kills you," Valve's Chet Faliszek said at EG Expo (via VG247). "And you die. You don’t come back."

"You can use the defib to get back, but your team has to do that for you," Faliszek added.

By 'glows,' he means the colored outlines around your teammates that make them easily visible from far away and through walls. They're normally blue and turn yellow if a teammate's been knocked down or grappled by a special Infected. Really helps stragglers, too. "The first time you turn around, and you run off by yourself and you’re going to get something out of this building, and you turn and go, ‘I’ve got the pipe bomb! Oh, man, where is everybody?’ And you have no idea. It’s a really different experience."

Pre-order customers have had access to the demo since last week. It's available to all Xbox Live Gold members as of this morning and PC owners should get their hands on it today as well.