The game places the player in the fictional post-Soviet Republic of Chernarus (based on the real life region of Ústí nad Labem in the Czech Republic), the original setting of Arma 2, where a mysterious plague has turned most of the population into violent "infected".

In December of 2019, the very first DLC terrain was released, setting players in the fictional Polish-speaking country of Livonia, directly ported from Arma 3.

DayZ began development in 2012 when the mod's creator, Dean Hall, joined Bohemia Interactive to commence work on the standalone version of the game.

The goal of DayZ is to stay alive and healthy during the conditions of the zombie outbreak that have befallen the in-game world.

The player spawns in a random area usually near the coast, equipped with only simple clothes, a glow stick, a bandage, and a piece of fruit, and must begin exploring the large 225 km2 (87 sq mi) landscape of the fictional former Soviet Republic of Chernarus to investigate locations such as houses, barns, and apartments to scavenge supplies.

[6][7] Beyond the basics of survival, players can find various forms of clothing, which allow customization, extra storage space for supplies, and warmth.

These are largely focused on a range of melee weapons, but a number of firearms are present, along with attachments such as suppressors and telescopic sights.

The game features dynamic events such as randomly spawning train wrecks, police situations, military convoys and helicopter crashes that contain high tier equipment and firearms.

[9] While travelling the map, players can also find various medical supplies, as the environment poses a range of threats to their characters.

Illnesses currently present within the game include the common cold, cholera, brain prion disease, salmonellosis and more.

The game includes a working horticulture system, with the option to both harvest wild plants and to grow one's own crops.

Vehicles are available to cut down on time needed for travel, provided that the player is able to locate one, restore it to working order, and keep its gas tank and radiator filled.

One of the developmental focuses was making the world feel more realistic by increasing the number of enterable buildings.

[15][16] Hall stated that he hopes to implement bad ideas into the game, in order to find what players enjoy, rather than taking no risks at all.

[17] The game is based on a client–server architecture, where functions such as item and NPC spawning are decided on the server, rather than on the player's machine.

[19][20] Following the troubled release of the similar game The War Z, Hall stated in a post on Reddit that the "whole 'saga' of the development made me seriously question if I wanted to be involved in the industry" and that he had considered leaving the DayZ standalone project.

[55][56] In an alpha review of DayZ, Rick Lane of Eurogamer commented positively on the new additions but said that the game may not be worth the current price until more features have been added.

[62] The ban was eventually lifted after Bohemia edited the game in order to fully comply with the Australian Classification Board.