State of Decay focuses on survival tactics: stealth, evasion, distractions, base building, survivor community, securing resources, and moving through the world more than actual zombie combat. The game is in an open world, where the player’s choices are an important factor. Players are able to choose from a large variety of locations to build a base in. Structures such as watch towers, gardens, sleeping quarters, kitchens, workshops, medical bays, and barricades can be constructed to defend against the infected population, help survivors recover faster, and build explosives and other tools.
Food, medicine, shelter, ammo, and construction materials are necessary for survival and should be used wisely. To obtain these supplies, the player will need to go on raids to abandoned supermarkets and many other locations, although food can be grown at the base. The player can also find other groups of survivors that are willing to trade their resources with the player, in exchange for ammunition. The player will be able to rescue other AI survivors to help with defense, build facilities, and repair cars/guns (with the appropriate facilities). They can also be sent out to loot, find a new base location, or to come pick up supplies found by the player. If one was to get enough supplies they are able to craft items like a homemade suppressor but have to wait 30 real world minutes while it is being made. Once a high enough relationship is developed with these new characters, they will become playable. The player’s choices will affect how the gameplay evolves. The game world is 16 square kilometers but because of mountains, it is 8 square kilometers of playable area.
The non-player characters (NPCs) in State of Decay will vary in skin color and gender and they will sometimes show signs of aging in the game. They can set up bases to survive which the player character can find while exploring. Saving NPCs will add them to the community of survivors. Each NPC can be assigned tasks like doing runs to collect items or do scouting. If the player is friends with an NPC and has a high enough influence, and the NPC has joined the player, they can ask the NPC to come explore with them. Characters can trade with other survivor bases for items which they excel in, such as weaponry. NPCs can become trapped when on a run for items, although the player will have the option to rescue them. If they are not rescued, they may die or become lost. If morale or supplies dwindle too low, Survivors may abandon the home and leave. They can form their own enclaves and may be persuaded to rejoin the player. There are 30 NPCs in State of Decay which will spawn in a semi-random arrangement, while 20 Story NPCs will always spawn in a designated location. Zombie NPCs come in various sizes, genders, and races. When the player’s character dies it becomes permanent and the player must continue without them. Characters killed by zombies may also turn into zombies, using “zombified” models of their original survivor. In addition, there are several “special” types of zombies that randomly appear in the game world, such as animal-like “Ferals”, that can pose a dire threat to both the player and survivor NPCs. If a horde of zombies is left unchecked for too long, they can cause an area to become “Infested”, reducing survivor morale at the home base and continuously spawning zombies in the general area until the player clears the area.
The game features 99 different weapons, including between 30 and 40 melee weapons to be found around the game world. The higher a character’s skill with guns, the lower the chance of them jamming. Jammed guns will need to be repaired at any home base. High skills with guns will also result in lower recoil. Gunshots will attract zombies; to combat this weapons can be equipped with suppressors. Each gun has a decibel rating seen in the game’s inventory; higher decibel ratings result in louder gunshot. There are three classes of melee weapons featured in the game; light blunt, light edged, and heavy weapons. Each class will have its advantages and disadvantages. As characters use weapons, their skill will increase.
During the game, player characters can enter a variety of buildings and areas. While loot will often be found, so will zombies. Fenced buildings can be turned into a base. Only one base can be occupied at a time, they can be overrun, and relocated. A large number of customization options exist for the base, including, but not limited to, gardens, kitchens, sleeping areas, storage areas, radio station for communication(comes automatically when base is inhabited by player), workshop for upgrading and repairing weapons and repairing cars, as well as creating items such as homemade suppressors and firecrackers, training centers, and guard towers. Almost all bases come with some building areas already built, and some may come with special building that cannot be upgraded. Any building that is not destroyed can be turned into an outpost. An outpost is a place for players to sleep in or store items. The number of outposts available to players is dependent on the size of the player character’s base. Zombies may spawn near outposts and bases periodically, and can even overrun them, depending on how well-supplied, populated, and well-armed the bases and outposts are. There are also occasional “Zombie Horde” events, where a large number of zombie groups will encroach on the player’s home base. If they are not dealt with, they will attack the home and may kill friendly NPCs while doing so. Survivor enclaves the player encounters can also be overrun and zombified.
Another feature of the game is dynamic progression; the game world continues acting whether or not the game is being played. If the game is not being played, friendly survivors within the home can still use and gather supplies, explore, and possibly be injured. Some characters may take weapons and ammo from the supply cache and may level up their abilities. New survivor enclaves can appear or disappear, cars the players’ survivors own can be repaired, and weapons can be repaired. Non-plot-essential NPCs can become injured or fatigued with the player absent, but cannot die nor abandon the base. This game is not recommended for children because there are many scenes of violence.