Language: English, spanish, russian, french, german.

Darkest of Days takes the player through time into historic battles in an effort to save key individuals from certain death. The battles range from Custer's Last Stand at the Battle of the Little Bighorn in 1876 to fighting in Pompeii as ash and fire rain down from an erupting Mt. Vesuvius in 79 AD. Other locations include the battles of Antietam and Tannenberg, and the German World War II prisoner of war camp Stalag Luft III. There are different missions in every time period and the game takes about 5ΓÇô9 hours to complete.

The game features various weapons, both from the time period in which a level takes place and from the future. In most cases, however, a player will not be using modern weapons unless they have been taken from killed Opposition agents. There are also brief segments where a player can take control of artillery or a cannon.

Players are required to save certain individuals who are important to the continuity of history. There are two types of characters who fall into this category. The first type is the individual who must be returned to the correct time locus; this type is highlighted by an orange aura. (Enemies, however, will not specifically target an orange aura character, and there is no special need to pay attention to them). The second type is a random character marked with a blue aura; such characters can be saved by being taken out of battle without being killed. (This can be done through the infliction of an arm or leg wound, or by the use of the "chasers" Stun weapon).

If three of the blue aura individuals are killed by the player, however, this can trigger a visit by the Opposition who use the disturbance caused by their deaths to track down and attempt to kill the player. Opposition agents tend to be heavily armed and shielded making many period weapons useless against their superior technology. They are not completely indestructible, however, and can be killed allowing the player the opportunity to seize their weapons. However, the downside of killing blue aura individuals to trigger opposition agents is the forfeit of any weapon upgrade points.