Gameplay Modes

There are 3 Gameplay Modes in Left 4 Dead.

Single Player Mode
This gameplay mode is for people who don't have internet connection. You play as one Survivor while as the other Survivors are AI-controlled. This mode is also for people who don't like to get team killed by other players.

Versus Mode
In this gameplay mode you work with other people around the world. Four human players play against four boss infected, which are also controlled by other players. This gameplay mode is currently the only mode where human players can choose to play as the boss infected.

The player controlled infected spawn 20 seconds after they are killed. They can choose their spawn location and ambush The Survivors easily.

You choose a specific campaign to play, then the first team plays as The Survivors while as the others play as the boss infected. The map lasts until The Survivors reach the end or they are killed. Then the teams switch the spots and move to the next map in the campaign.

Campaign Mode
You and three other players work together to survive. There are four difficulty levels: Easy, Normal, Advanced and the most difficult: Expert. This is a survival mode. The infected are AI -controlled