The Castle Doctrine is an indie MMO title from developer Jason Rohrer that was released on January 29, 2014. The game requires the player to construct a secure house to protect the contents of a safe before attempting to rob the houses of other players. Should the player die during a robbery attempt, they must start over from scratch with a new house.
The player begins with a set space in which a house can be built, a safe, a wife, and two children. Houses are limited to a single story with no basement. The safe and family members can be placed anywhere within the house. However, a requirement for building a successful house requires that there be a way to successfully navigate any traps or obstacles to reach the safe, and players must succeed in a test run of their houses before they can be published online. Family members must have a clear path to the entrance in order to escape when seen. The player can design the layout of the house, choose the material that the walls are made of (with the strength of the material tied to the cost), and lay out traps such as electrified grating on the floor or pit bulls that will stalk and attack would-be robbers.
Prior to engaging in a theft, the player may purchase equipment to bring along to assist in bypassing a house's security measures. The player must then select a house to rob, with potential targets appearing in a list denoting the name of the owner, the amount of money the house currently has, the number of robbery attempts on the house, and the number of successes. Players may not choose to rob houses that they have either attempted to rob before or that are actively being robbed at that moment.
Once inside a house, the player has the option of backing out and leaving if the obstacles appear to be too overwhelming to handle. Otherwise, the player's goal is to avoid the home's security obstacles and reach the safe. It is not required that the player escape the house after accomplishing the objective.