Day of Defeat: Source

There are two main game modes in Day of Defeat: Source: territorial control and detonation. In territorial control maps, players must fight for control of all strategic points on the map.[6] The strategic points take various forms, such as a destroyed tank in a street or fields and buildings, and are designated by a flag in its vicinity, which displays the army colors of the team who controls the point. Points are captured by a certain number of team members surrounding the point, with it either capturing instantly or after a couple of seconds.[6] Players on the other side can disrupt a capture by placing themselves within the capture area during the process or by killing the enemy players at the point. The first side to hold all the points simultaneously wins the round.[6]

The objective in a detonation level is to plant and detonate explosive devices on a number of enemy positions, which can consist of anti-aircraft guns, tanks and armored cars. Some positions must be hit twice for them to be destroyed. Players can protect their positions by defusing the explosives before they detonate.[9] In one variation of this game mode, one side has to defend their positions for a set amount of time, with the destruction of each piece of equipment giving the enemy team more time. The defenders win if they can hold their positions long enough for the time to run out, while the attackers win when all objectives have been destroyed. In the alternate version, both teams must attack the other's objectives while defending their own. The first team to destroy all of the enemy's equipment wins.[9]

A German rifleman takes aim. The destroyed train station in the background forms one of the game's strategic points.

Both factions in Day of Defeat: Source have access to six classes. Each class is designed with specific combat circumstances in mind, so that teams must use teamwork to succeed. The weapons and equipment carried by the classes are based on the weapons used by both the US Army and Wehrmacht during World War II. Some of classes are armed with pistols—the American M1911 or the German Walther P38—while others are equipped with trench knives or entrenching tools for melee combat.[10] Grenades are carried by a number of classes, depending on their role in the game—riflemen are equipped with rifle grenades, the assault classes are armed with a single fragmentation grenade and a smoke grenade for providing concealment, while support classes have access to two standard fragmentation grenades.[10]

Day of Defeat: Source was first announced for Microsoft Windows during the development of Half-Life 2, the flagship game of the Source engine, as one of several of the Valve's GoldSrc powered games to be remade on the new game engine. In the aftermath of the release of Half-Life 2 and Counter-Strike: Source, very little information was released regarding the development of Day of Defeat: Source until 2005. In February 2005, Valve announced Day of Defeat: Source, stating that the game was nearing its beta development phase and would be available later in the first quarter of the year.[11] The game was opened to an internal beta test soon after, which certain members of the Day of Defeat community were invited to join. The beta version of the game was shown as a straight conversion of the most recent version of Day of Defeat, at the time even including the same player and weapon models as the game's GoldSrc counterpart. Due to the response of the beta testers, significant changes were made to the gameplay, taking it away from being a straight conversion: the behaviour of weapons was altered and several classes from Day of Defeat were dropped entirely. Later media releases showed the revamped version of the game, including its new player and weapon models, as well as new additions to the game, such as rifle grenades and smoke grenades. On September 2, 2005, Valve announced that they were "confident" that the game would be released that month,[12] and seven days later announced an official release date of September 26, 2005.[13] The game was made available for preload via Valve's Steam content delivery system on September 14, 2005,[14] and was officially released on time on September 26.[15]

Day of Defeat: Source has undergone several updates. These updates have consisted of gameplay tweaks, maps and graphical effects. The first new level was released on November 30, 2005, and was followed on January 25, 2006 by another map, used as a demonstration for the Source engine's abilities in rendering snow and ice.[16][17] A major update was announced on June 22, 2006, adding the detonation game mode, various gameplay tweaks and two further maps to accommodate the new game mode.[18] The update was released on June 28, 2006.[9] On April 26, 2007, a group of maps produced by the game's community, entitled the Community Assembled Map Pack (CAMP1), was released.[7] Consisting of three maps, the pack was created with the assistance and support of Valve.[19] This was followed by CAMP2 on July 26, 2007, a pack which consisted of a further five maps.[8] On May 23, 2008, Valve announced another major update to Day of Defeat: Source, this time giving the game support for the company's new Steamworks programmer. The update is open to any owners of Day of Defeat: Source. Along with various gameplay tweaks, the update moves the game to the Source engine version used with The Orange Box, allowing the game to utilize particle effects, as well as adding a map based on a long-standing custom map for Day of Defeat and 54 achievement awards for players completing certain tasks.[20][21]

Depth of field, color correction and film grain effects used in the trailer

Day of Defeat: Source has been used by Valve as a platform for demonstrating several technologies in the Source engine. Day of Defeat: Source introduced a dynamic audio system that was limited to non-player characters in Half-Life 2.[5] The sound of each weapon firing in-game is attributed with distance and occlusion variables, which are processed and then fed back to the player. Sounds far from the player lack higher frequencies and thus sound more like they naturally would, allowing for the actions of other players on a map to make up the ambient sounds for the level.[5] The game was the first to incorporate Valve's high dynamic range rendering, predating the official demonstration, Half-Life 2: Lost Coast.[22] Other effects were added post-release to make the game appear as if it were a World War II era film. The effects include motion blur,[23] depth of field,[24] film grain[25] and color correction.[26] Phong shading on the Source engine was added to Day of Defeat: Source with the major update in the second quarter of 2006.[9]

To promote the game, Valve has produced three machinima trailers depicting the game in play. The trailers are themed around wartime propaganda news reports for both Germany and the United States. To convey this effect, the trailers make extensive usage of the Source engine's capabilities for film grain, color correction, motion blur and depth of field, as well as sepia toning. The first trailer was released as part of the game's post-release marketing on December 20, 2005. Entitled Prelude to Victory, the trailer depicted a large firefight in the game as a report from the German perspective, complete with a commentator speaking in the German language.[27] Two further trailers were released to promote the major update to Day of Defeat: Source in the second quarter of 2006. The trailers, both from the American viewpoint, displayed how the new detonation gameplay worked, emphasising teamwork as the key to success, as well as introducing the viewer to the two new maps added by the update.[28][29] To further create interest in the game, Valve has opened Day of Defeat: Source to three free weekends, the first taking place on February 10, 2006,[30] the second on July 8, 2006[31] and the third on July 4, 2008,[32] where anyone with a Steam account could download and play the game for a maximum of 48 hours free of charge.