Set in the Second Battle of Fallujah of the Iraq War over the span of six days in November 2004, the game follows the United States Marine Corps' 3rd Battalion, 1st Marines (3/1) as they fight the Iraqi insurgency in the city of Fallujah, Iraq.

Around 2016, Victura and Highwire began developing a revived version of the game, which was announced in February 2021.

[5] Tamte later stated that "When they came back from Fallujah, they asked us to create a video game about their experiences there, and it seemed like the right thing to do.

"[4] Tamte stated that the goal of Six Days from the start was to create the most realistic military shooter possible, and that "Ultimately, all of us are curious about what it would really be like to be in a war.

[8] The game's director, Juan Benito, elaborated that "Through our interviews with all of the Marines, we discovered that there was an emotional, psychological arc to the Battle of Fallujah.

"[8] According to one of the developers who worked on the game, the development team also consulted non-fiction books about the battle as part of their research, such as Patrick K. O'Donnell's We Were One: Shoulder to Shoulder with the Marines Who Took Fallujah, incorporating their recollections into the game's events and story-line.

"[15] Atomic Games stated that Six Days would feature destructible and degradable environments using a custom rendering engine, which they claimed surpassed the destructible environments of the Battlefield series, let alone any game released or in development at the time.

[16] Atomic Games clarified these destructible environments were not a "goofy, out-of-place marketing gimmick", but a deliberate feature to reflect the actual Battle of Fallujah, during which U.S. Marines used explosives to breach buildings and demolish structures insurgents were hiding in.

[18] IndustryGamers reported the following day that, per a source, "Out of 75 people, less than a dozen are left and about a third of that isn't even developers.

[22] On August 26, 2012, Tamte informed Digital Spy that Six Days was "definitely not canceled" and remains "very important".

[23] In 2018, Tamte again stated that the game was not cancelled, that the assets were still intact, and that it would eventually be finished and released at an undetermined future date.

[25] After a dearth of reports over its developmental status throughout the year, the developers announced that the game would be delayed to 2022 due to a lack of manpower, resources, and time.

[38][39] Some features in the game were also criticized after its release; for instance, James Troughton of TheGamer noted interview footage and information presented in loading screens were all from U.S. Marines and thus only presented an American perspective on the battle without any commentary from Iraqi civilians.