Another visual aspect that the Valve team explored was the rendering of water, particularly in the "Swamp Fever" campaign, which takes place mostly in a large swamp area. Valve found early play-testers would become confused with the large, tree-covered map, but by adding hints of water movement in the direction they were to go, there was a significant reduction in players becoming lost on the map. The water maps were created by using the 3D animation tool Houdini against its landscape maps to create realistic water flow patterns as surface maps. These surface maps were then applied in a "flowing" manner instead of the scrolling manner used in previous games. These water effects were further expanded upon for Valve's next game, Portal 2. [81] Faliszek stated that Left 4 Dead 2 's story would explore more of the world of the game, and that Valve had created a full story for the cause and effects of the infection pandemic, including terms that they have used for the AI Director. [75] Each campaign was purposely designed with a different feel; however, all five campaigns were mapped out at the same time by the entire team to provide the narrative flow and ensure the uniqueness of each campaign. [76] The team used a Left 4 Dead dictionary developed to describe level design and flow within the game to provide a common language for developing the levels. [76] On May 10, 2011, Doug Lombardi mentioned that each of the Left 4 Dead games had sold three million copies on the Xbox 360. [158] In September 2012, Faliszek, in an interview with VG247, said that the series had sold over 12 million in total. [159] The game was offered free for a day on Steam during Christmas 2013. [160] [161] Controversies [ edit ] On August 20, 2015, an update for the game Zombie Army Trilogy was released, which imported the eight survivors from both Left 4 Dead games into ZAT. [115] In 2021, the characters were added to the games sequel Zombie Army 4: Dead War. [116] Mutations [ edit ] Goslin, Austen (July 1, 2021). "Left 4 Dead doesn't need spiritual successors, it needs updates". Polygon. Archived from the original on July 1, 2021 . Retrieved July 1, 2021.

Valve On Left 4 Dead Servers & Matchmaking". Voodoo Extreme. November 10, 2008. Archived from the original on January 29, 2009 . Retrieved December 10, 2008. a b Valve. Left 4 Dead 2 (2.1.0.7ed.). Valve. Level/area: Dead Center, Stage 3. Coach: [as the group prepares to leave the saferoom] Keep an eye out for the evac center. ...Also, the food court. I am starvin '!Avon Oeming, Michael. "The Sacrifice". Valve. Archived from the original on March 1, 2021 . Retrieved October 4, 2010. Chan, Norman (July 21, 2008). "E3 2008: Left4Dead Interview. New Graphics, Weapons, and Steam Achievement Details". Maximum PC. Archived from the original on October 29, 2008 . Retrieved October 26, 2008. Yin-Poole, Wesley (2008-10-09). "Valve details post Left 4 Dead launch plans". Videogamer.com. Archived from the original on 2012-04-18 . Retrieved 2009-06-04.

In Versus, there are two teams of four players each. They play each chapter as both Survivors and Infected, swapping sides after each round. [23] The infected team are given vertical pathways, such as pipes and vines, which can be climbed and used for ambushes. Dead survivors do not respawn. If at least one player reaches the safehouse, the survivor team earns 100 points, as well as bonuses based on their health, and the health items still in their inventory. These points are multiplied by the chapter's difficulty level, and the number of survivors who lived. If all survivors are killed, the survivor team only earns points from their progress through the chapter and the difficulty multiplier. [24] The victor is decided by which team scores the highest during the campaign. Williams, Bryn (2010-03-08). "Left 4 Dead 2: Mac and PC Versions are Cross-Platform Compatible". GameSpy. Archived from the original on 2010-03-10 . Retrieved 2010-03-09. Personalize your apocalypse". Valve. May 13, 2009. Archived from the original on June 4, 2009 . Retrieved June 13, 2009. In introducing the new Infected, the development team had to consider how the new abilities would mesh with the existing Infected and any changes they had made to them. [76] One discarded idea for a new Infected included the "Leaker"; the creature, when having taken damage, would shoot out spouts of goo at the survivors, and then would be able to self-detonate like the Boomer. However, this sacrificial act would have given survivors time to escape, and the idea was dropped, though features of the Leaker were built into the Spitter. [76]

Left 4 Dead Afterthoughts". 1up.com. Archived from the original on January 18, 2016 . Retrieved January 19, 2009. We actually started out with a single, huge city design with a great many routes for the survivors to take to reach the extraction point. As we began to playtest in this zombie city, we immediately discovered that having that much choice combined with the chaos of zombie hordes made for frustrated and paralyzed survivor teams Today's Announcements: Super Mario Bros 2, Monster Hunt 4, Gears of War: Judgement, Left 4 Dead 2: Cold Stream". Archived from the original on 2012-07-03 . Retrieved 2012-07-03.