In Darkest of Days the player controls Alexander Morris, a soldier fighting in General Custer's battalion during the Battle of Little Big Horn at the beginning of the game.

Morris then awakens in the headquarters of Kronotek, an organization that has managed to develop time travel technology and is apparently dedicated to researching and protecting history.

Although Agents Morris and Dexter manage to secure and reintegrate Welsh and his twin brother into the proper timeframe, Petrovich is labeled a traitor for abandoning his post.

After rescuing Petrovich, Morris and Dexter find out that Koell is at Pompeii, on August 25, 79 AD, the day Mount Vesuvius erupted and buried the Roman town.

When confronted by Morris and Dexter, he explains that the Welshes and Petrovich were ancestors of scientists who invented a DNA sequencer that can target the genomes defining racial identity.

The strange man then says that his Kronotek has use for talented agents such as Morris and Dexter and invites them to join his agency, leaving an open time bubble for them to enter.

They incorporated extensive research on the time periods, locations, and weapons for each of the battles depicted in the game (much of the city of Pompeii is accurately recreated).

[4] "It was critical to the success of Darkest of Days that these epic moments in world history are experienced in eerily accurate detail, and NVIDIA PhysX technology helped us achieve that goal," said Mark Doeden, Art Director at 8monkey Labs.

"Our Marmoset Engine brings these battles to life with a completely unique look, and the PhysX technology was instrumental in making the game feel alive and real.

The Marmoset engine can handle over 300 characters on the screen at one time, enabling the game to have densely populated battle scenes, all with their own AI and pathfinding.

All actions share a common set of sensory data - audio, vision, navigation, teammate signals, enemy fire detection, and object finding and following are all easily made available to all behaviors.