Day Of Defeat: Source

While Day of Defeat's classes were relatively flexible, Day of Defeat: Source limits them to ensure that each has a clear set of advantages and disadvantages. This is achieved through modifications to weapons, a class' weapon loadout, and varying degrees of 'cone fire' for different classes.

The clearest example of class specialization is the rifle class. In the original Day of Defeat, riflemen were equipped with a pistol and could attack players with the butt of their weapon. This gave them several fallbacks should they find themselves in close range combat or other dangerous situations. In Day of Defeat: Source, riflemen do not have sidearms nor can they attack with the rifle butt. They can now bring up the rifle's iron sights for increased accuracy and have been equipped with trench knives and entrenching spades. In addition, in place of standard fragmentation grenades, rifle players are equipped with two rifle grenades. These grenades are capable of being fired over a much larger distance than standard fragmentation grenades and are able to strike at enemy sniper and MG positions with relative ease. Their disadvantage is that they are not easily primed or especially useful in close combat situations where a fragmentation grenade would be. This in turn specializes the class solely to medium to long range situations and players learn to avoid close quarters combat.

Similar changes have been made to other classes, and the result is that a player will usually have to consider carefully where he or she moves, in order that they are not countered by a more suitably-equipped player. Class specialization also reduces the potential for one player to dominate in the game, and encourages teamwork amongst players.

Real-time physics

Real-time physics are a by-product of Day of Defeat moving to Valve's Source engine. Like all other Source engine games, these are powered by a heavily modified version of the Havok Physics engine.

In the game, the engine gives the player the ability to modify the environment for a more favorable position, as they might in a real firefight. The movement of furniture indoors to block off a door, or pushing a table into a position and using it as makeshift prop for a machine gun are examples of players utilizing the physics to their advantage. Notably, players' helmets provide realistic protection against enemy fire, and a correctly placed shot is even capable of removing a player's helmet without killing him. However, the protection commonly goes unnoticed, as the most common sound to be heard accompanying a death is the tink of a bullet hitting your helmet, followed by the sounds of it scraping rock and dirt.

More cosmetic changes include fully simulated debris and ragdoll animations for dead players.

Dynamic audio simulation

Day of Defeat: Source introduces a dynamic audio system that was limited to NPCs in Half-Life 2. Day of Defeat: Source is the first Source game to fully utilize the dynamic audio system in online multiplayer games.

In Day of Defeat: Source, each sound 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, for example, abrupt pops for gunshots. Doppler effects, occlusions, and directional sound are also present features.

With machinegun fire, this method appears awkward, however, as the cutoff for sound changes can be a few steps, or simply be within clear view of the shooter at ranges which make the gunner sound much farther away than they are.

Trajectory randomization

In addition to recoil, which modifies the perceived projection of the bullet trajectory, a system for randomizing the bullet trajectory outside of a physically controllable system is present. This system relies on calculating a random angle within 2 discrete values creating an angled trajectory from the physically perceived angle. The maximum values that can be calculated, if graphically represented, create a cone, dubbed the "cone of fire".

It was initially believed that Day of Defeat: Source featured larger maximum angles than its predecessor. Following experiments by ex-Valve employee Tim 'Waldo' Holt, where weapons were fired in controlled in-game environments, it was found that this was only true of submachine gun and pistol weapons. The results of the experiments were posted on the official forums.

Release

Day of Defeat: Source was released over developer Valve Corporation's Steam service at 22:00 GMT on September 26 2005, and was subsequently released in stores on September 28 as a part of the Counter-Strike: Source package. Day of Defeat: Source was released in retail as a Stand-Alone Product for $19.99 USD. It was later reduced to $9.99.

Unlike Half-Life 2, the game's release on Steam went smoothly, with large IRC parties and live radio shows organized by fans adding to the sense of anticipation. Indeed, the release went so well that players soon found every server full, and only poorly-configured and laggy listen servers with free slots.

Future development