What u have to do is go to left 4 dead 2 and search for sacrifice and the passing and you have to buy the missions and if u don't want to then you have to get an account and play it online
its easy all you have to do is at the main menu go to campaign the act as if you are going to select a normal level then press the passing insted you can also play mutation with the passing
if you have the passing , their is a mutation called last man on earth
You can purchase The Sacrifice DLC for Left 4 Dead 2, which has you play as characters from the first game. Additionally, you can put character skins of the original characters onto the characters of Left 4 Dead 2 (Only in the PC version)
(CAUTION: This answer contains information that may spoil the campaign(s) if you have not yet played them.) They meet in between the Left 4 Dead 2 campaigns Dead Center and Dark Carnival in a download-able campaign called "The Passing", which is soon after the campaign for both Left 4 Dead 1 & 2, The Sacrifice. The Left 4 Dead 2 survivors are driving through an infected town and the bridge is out, Francis or Zoey will tell you that you have to gas up a generator to get across because it has no energy left from when they raised it. Louis has a hurt leg so they can't leave him alone, and Bill got taken out by a few tanks, you will see the bloody result in the room of the scene. In The Sacrifice, where you play as the original survivors, any one of the survivors can sacrifice themselves to restart the malfunctioned generator to raise the bridge, but it will always appear as Bill in The Passing.
4 players can play in Left 4 Dead 2.
Left 4 Dead can be played on either PC or Xbox 360.
Yes, you can play left 4 dead 2 on steam if you buy from Gamestop.
Yes you can play online
You have to download Steam on your computer, then Left 4 Dead 2 can be bought from that.
One can definitely play Left 4 Dead on their own. But it is more enjoyable when other people are dying along with you. :)
which laptop?
nope