Day of Defeat

Day of Defeat is an online game from the makers of Half-Life and Counter-Strike taking place during WWII in Europe. The player joins a team of an elite military squad in deep battle. These elite teams are made up of players of different classes like scout, infantry, sergeant, and machine gunner. Each player class has a unique arsenal at their disposal.

The game has a large collection of missions based on historical battles. It's also possible to download additional missions that have been created by the online development community.