[1] The game takes place two years after a pandemic killed almost all of humanity and transformed millions of others into "Freakers", mindless, zombie-like creatures that evolve quickly.

[15] Players can complete objectives in multiple ways, such as by using stealth tactics to distract enemies or silently kill them from behind using a combat knife.

[11] Alternatively, players have access to a wide variety of firearms such as pistols, shotguns, sniper rifles, submachine guns and crossbows.

Deacon sees a NERO helicopter and follows it, eventually meeting James O'Brian (Bernardo de Paula), the researcher who evacuated Sarah two years earlier.

Unwilling to send Lisa back to the Hot Springs, Deacon arranges for her to shelter with Rikki Patil (Nishi Munshi), a former drifter and member of the Lost Lake camp led by "Iron" Mike Wilcox (Eric Allan Kramer) and Raymond "Skizzo" Sarkozi (Jason Spisak), the former of which parted on bad terms with Deacon over his violent behaviour and dubious morals.

Boozer's condition worsens and, in an act of desperation, Deacon sneaks into Lost Lake to steal medical supplies but is caught.

Despite the bad blood, Deacon is able to convince Iron Mike to allow Boozer to stay and later learns that Lisa fled from the camp and remains missing.

Deacon realizes that Sarah, a government researcher with federal security clearance, would have been prioritized during a camp evacuation, and O'Brian confirms that she was moved to a military outpost at Crater Lake, which is now controlled by the Deschutes County Militia.

Deacon meets Derrick Kouri (Phil Morris), a Captain for the militia wearing Sarah's Mongrels ring, and is brought back to the Crater Lake outpost.

Deacon then wins over the militia's leader, Colonel Matthew Garret (Daniel Riordan) and reunites with Sarah, who is working to create a bio-weapon to destroy the Freakers.

Garret, shown over time to be a religious fanatic, reveals that he believes other human factions are a bigger danger than the Freakers, and declares a holy war against all other camps.

Returning to Lost Lake just in time to assist in the defense against the militia's attack, Deacon finds a mortally wounded Iron Mike who dies shortly after.

Deacon rallies the remaining members of the Lost Lake camp and, with the support of other nearby settlements, retaliates against the militia by attacking their headquarters with a truck bomb.

According to Garvin, Central Oregon has diverse terrain and landscapes ranging from snowy mountains to deserts, making it an ideal setting for a sandbox title.

The team spent a lot of time working on the group artificial intelligence (AI) to ensure the horde would not only charge at Deacon in a straight line but would also make use of the terrain to overwhelm the player character.

[26][27] Garvin added that despite the game's post-apocalyptic setting, the team aimed to deliver a more hopeful theme because the story of Deacon concerns the way he can make the world a better place and explores the idea that surviving is not the same as living.

[37] Garvin, who was impressed by his work on The Purge: Anarchy, invited Nathan Whitehead to compose the music for Days Gone,[38] which was performed by the Nashville Scoring Orchestra and soloists.

[40] Whitehead added that the game's music, which combines "folk Americana and a touch of rock elements", is a good fit for the setting.

[45] As part of Sony's efforts to bring more of its first-party content to personal computers following Horizon Zero Dawn, Days Gone released for Windows via Steam and Epic Games Store on May 18, 2021[46] and via GOG on October 25, 2023.

Lavoy, however, noted the small scale of the map and criticized the way Days Gone uses environmental obstacles to force players to navigate longer distances.

[64] Several reviewers felt that the world is empty and sparse because the game's locations were not given a strong visual identity or backstory, making exploration meaningless.

[56][67] Kato described the experience as "terrifying" and "tense", and applauded the artificial intelligence for being unpredictable, meaning that different trials may lead to vastly different outcomes.

The motorcycle, which was the only way to navigate the world, received mixed opinions, with Hurley adding that he slowly grew attached to Deacon's bike because the game required the player to care for it during the campaign.

[80] In January 2022, Days Gone's director Jeff Ross claimed on Twitter that the game had sold over 8 million units by late 2020.

[84] On April 9, 2021, Jason Schreier of Bloomberg News revealed Bend Studio had pitched a sequel to Days Gone but that the first game's mixed critical reception and lengthy development process caused Sony to reject the proposal.

He revealed that part of the plan for the sequel was a "shared universe with co-op play," which was not included in the original Days Gone due to staffing constraints.

[103] While appearing on a podcast with David Jaffe, the creator of the God of War franchise, Garvin said, "If you love a game, buy it at fucking full price," and implied Days Gone did not receive a sequel partly because it did not turn enough profit.

[104] Garvin came under fire for his remarks; commenters said Days Gone had already benefitted from fan support during its release, and that it was unreasonable to ask someone to spend US$70 on an unknown game.

[105] Others noted that Sony ultimately controls sales of PlayStation games and offers free demos, and the blame could not be placed entirely on the purchasers.

[111] This was in response to the announcement that Ghost of Tsushima, another SIE first-party game (developed by Sucker Punch Productions), had sold over eight million copies.