During Campaign, also known as Co-op, up to four players work together to try and reach the end of the campaign by fighting their way past large numbers of AI-controlled Infected. There are four difficulty: Easy, Normal, Advanced and Expert. Each chapter ends in a safe room, which acts as a checkpoint that is triggered when all living Survivors get inside the safe room and close the door behind them.
In Campaign mode, one or more players play as the Survivors, with the rest of the four filled in with AI-controlled "Bots". The Survivors play through each chapter, making their way from safe room to safe room. The last stage in each campaign has an expanded ending called the Finale, which usually ends with players escaping on Rescue Vehicles like boats, helicopters, etc.
If the Survivor dies at any point before the Finale, they will respawn in a Rescue Closet after some time and ask for anyone to get them out or in a safe room when the next map loads. Also, if all Survivors are dead or incapacitated, the campaign's current chapter will be restarted with all the weapons and items they had in the safe room when loading into the map. However, should the players die and leave the bots alive during the Co-op mode, the game acts as if all Survivors were dead, triggering the chapter restart.
Single Player is a gameplay mode with only one player controlled character. The player assumes control of one of the Survivors, and all the other characters are AI controlled. No other player can join a Single Player game, unless locally (LAN), via the connect "host local IP" console command. Other than that, the same rules as Campaign apply here, except for in Dead Center, or The Passing where you only have to get 8 Gas cans in Solo Dead Center (13 in standard Campaign mode) and 10 in Solo The Passing (16 in standard Campaign mode) to compensate for the fact A.I.-controlled Survivors never attempt to pick up the gascans.
Single Player is the only mode which can be played with Steam in Offline mode. Since Single Player is considered as local server, modifications that work only on local server will also work in this mode.
This is also the only mode that allows you to fully pause the game (i.e. halting the in-game time by bringing up the menu). In other modes, this can only be done when playing as host on local server with command sv_pausable set to 1.
The (now) cut or former gameplay mode's image is Ellis holding the Krieg 552, a weapon from the German censored version of the game, which becomes available for everyone in The Last Stand Community Update. Interestingly, the image and the weapon do/did not exist in the international version at the same time (and Left 4 Dead has no images for game modes).
In Single-player, if you die during the Campaign, the chapter will restart since bots don't use Defibrillators (unless mods has been used to allow bots continue on their own). Also, if you complete the campaign with everyone surviving, it will say "The Survivors have escaped!" or "In memory of [name/s of deceased survivors in the finale]" if the player escapes but the bots failed. The only time Campaign can be completed with the player dying as a result is Port Finale of The Sacrifice Campaign, as bots are not programmed to go and restart the generator and therefore the player's death won't fail the campaign for balancing reasons.
Prior to the The Last Stand Community Update, the gameplay mode used to appear in Left 4 Dead 2 as a separate mode, however it has since been demoted into a drop-down menu option for all co-operative modes. Its former description isn't carried over to the current Campaign description.
In Split Screen, two players on the same console take control over two Survivors, and the screen is split vertically, although it can be changed to horizontal in the options menu. The two players can also play online while using split screen.
This game mode is normally exclusive to the Xbox 360 version of Left 4 Dead and Left 4 Dead 2, but may be accessed in the PC versions if you have a controller for the second player and modify some files or use mods. Here is a guide to how to play splitscreen on the PC. Plugging the Xbox controller in and out during the loading screen is NOT the only way to set the Xbox controller to player 2. During gameplay, you can also unplug and plug the Xbox controller back in within one second to set the controller to player 2. In fact, the second method proves to be more effective with several people. On Left 4 Dead and Left 4 Dead 2, only one of the two players playing splitscreen on one Xbox 360 console while online has to have an Xbox Live account with gold membership; the other player can sign in as a "Guest".
Survival was released in the "Survival Pack," which came out on April 21st, 2009. The point of Survival Mode is to hold out for the longest time, with times being saved and virtual medals being awarded for surviving for certain amounts of time. Left 4 Dead features sixteen maps, fifteen of which are taken from existing campaign levels, and one new map which has been called The Last Stand. The campaign levels have been edited to remove things such as closets and other small choke points often exploited by the Survivors in crescendo events and finales. Survival can be played in Single Player with Console commands or by starting a lobby on your own on Xbox.
In Left 4 Dead 2, Survival Mode is back, this time included with the release of the game. The point is still the same, and the maps are still converted crescendo events apart from The Motel from Dark Carnival's The Highway and The Sugar Mill from Hard Rain's map by the same name, among others. Single-Player Survival mode (with bot allies) is easily accessible this time.
Versus is the basic competitive mode for the Left 4 Dead series: two separate teams of four players take turns playing as the Survivors and the Infected competing for the most points. In Left 4 Dead, points are only awarded to teams playing as the Survivors. Points are calculated by the amount of health left in each player and how far the team got. In Left 4 Dead 2, points are still only awarded to the Survivors but no longer use the amount of health left in each Survivor in the score. Instead, points are awarded solely on how far each Survivor got before they died and if they made it to the safe room alive. The points possible for each chapter is the same for both teams. Should both teams make it to the safe room without casualties and without the use of a defibrillator, then the Tie Breaker calculates how much damage each team did to the opposing team, awarding 25 points to the winner.
Before a game starts, the lobby leader chooses a specific campaign to play and the players can choose which team to play on by choosing whether to start as the Infected or the Survivors. For help as Infected or Survivors, review some tactics.
Realism Versus follows the normal rules of Versus mode in terms of gameplay style and scoring, but makes things harder for the Survivors as they are bound to Realism rules, such as a lack of Survivor glows and the Witch being able to instantly kill Survivors. Though Realism Versus will appear in the main menu, you cannot play it unless you have downloaded The Passing.
Realism can be played on any difficulty setting. This mode removes the Survivor auras usually shown around players through walls. Also, halos for items or weapons only appear if you are close enough to do their action (such as grabbing a weapon or pressing a switch). Realism mode also includes a damage penalty for body shots. Rescue closets are removed, making the defibrillator the only way to revive dead Survivors until you reach the safe house, where they will respawn for the next round. Witches kill instantly on any difficulty except Easy and no longer receive bonus damage from point-blank shotgun blasts, making cr0wning impossible. Speech bubbles over the Survivors are disabled when speaking via the microphone, although the speech bubble still appears above the character's icon. Overall, this gameplay mode was created to take the teamwork factor that made the Left 4 Dead series famous to the next level. Realism can also be played by creating your own lobby.
Scavenge is a competitive gameplay mode in Left 4 Dead 2. It is a round-based gamemode in which Survivors have a limited amount of time to find up to 21 gas cans to fuel up a generator (or car), while fighting against player-controlled Special Infected much like in a Versus game. Games can consist of one, three, or five rounds total, though not all of them may be played. After all the Survivors are incapacitated, the time runs out, or the Survivors collect all of the gas cans, the teams switch sides. Whichever team collects the most gas cans in a single round wins that round. If both teams collect the same number of gas cans, the team that collected them the fastest wins that round. When one of the teams wins either one, two, or three rounds (if there are one, three, or five rounds total, respectively), that team wins the match.
Mutations are tweaks and changes to the normal game rules. They can be for any game mode, which will be introduced each week by Valve on the in-game blog. Details for the next Mutation are revealed on at the same time the Mutation is released on Friday, via the blogs. On regular intervals Valve initiates a "Favorite Mutation" survey, and winners are put back into the cycle.
Take the role of a different set of survivors as you use all new blunt force weapons, chainsaws and new guns in the sequel to Left 4 Dead. Teamwork is even more crucial as high intensity moments require greater communication to survive.
Left 4 Dead 2 is set at roughly the same time as the original just after the outbreak that turned most of the population into various zombie mutants. Players assume the role of four new "Survivors," each with their own personality and new dialog. The game leads these "Survivors" through the southeastern region of the US - from Savannah, Georgia through the bayou country, and climaxing in New Orleans French Quarter.