This War of Mine is a war survival simulation. The player controls a group of survivors trapped inside a building during a civil war. The goal of the game is to survive a certain amount of days, leading to one of six possible endings based on the decisions and events during the game. At the start, one of four survival groups is chosen, unlocked gradually. During the day the game is set entirely inside the single building where they seek shelter. They each have a bio, updated based on the events during the game, and a specific trait such as being a good cook, a fast runner or a skilled scavenger.
To survive they need to gather various resources so they can improve their life in the shelter. A small amount of items can be found inside the house, but most of them need to be gathered by scavenging at night as during the day snipers would easily spot them. The house is randomized for each session and also most of the events. At the workshop the survivors can construct household items such as a bed or a chair, but also workshops to cook, gather water and construct guns, and create consumables such as fuel, and filters to have clean water. Some constructions such as the workshop and the stove can also be upgraded and they can be placed anywhere in the house. The game is played in real-time, but it is possible to end a day prematurely if no more activities are available. At night one character can go scavenging, while the others sleep or guard. To scavenge, various items can be taken along and multiple locations become available gradually. They each have a short description to show what kind of materials are available and the amount of possible danger.
While scavenging stealth comes into play. There are often other people in the locations and they can be hostile or friendly. Locations can be revisited and the situation can have changed, for instance when another group raids the building. While scavenging it is possible to interact with other characters, fight using fists or guns, and hide. There are also ethical considerations, as a well stocked building can be inhabited by a pensioner who is unable to defend. These actions can come back to haunt the characters, making them depressed. The survivors are also affected by hunger, cold, tiredness, sadness and sickness. Bandages can be crafted as well as medicine, and while cooking food costs fuel, eating raw food heightens the chance of sickness. Items such as books, a radio of cigarettes can be used to influence the moods, as sad characters will often abandon their tasks. Lockpicks can be created to open locked doors and crowbars to break through grates by force. Guns are scarce and when only one is available the player has to choose between taking it to scavenge or leaving it for the guard.
Other events include groups that raid at night and steal resources, refugees that seek shelters, people that come to barter, survivors that choose to leave the building and characters that die while scavenging or from hunger or sickness, which also affects the remaining ones. A session can be saved to continue playing at a later time.