Valve have released a cinematic trailer for the upcoming Sacrifice update For Left 4 Dead and Left 4 Dead 2, due out October 5th. The trailer features a couple of situations that might illustrate the 'Sacrificial gameplay' Valve say the update will include. Francis disturbs a witch, Zoe has a last stand on a bridge and Bill, well, he charges three tanks with a molotov cocktail. Check it out.
