No Mercy

No Mercy is the first campaign in Left 4 Dead. It spans five chapters. In it the surviors are told by a passing Helicopter to get to Mercy Hospital to be evacuated. On there trek to the hospital they go through an apartment building, city streets, the subway, sewers, and finally through the hospital to the roof to be rescued by helicopter

Demo
The Left 4 Dead demo consists of The Apartments in its entirety, as well as the first half of The Subway.