In video game development, the door problem is an analogy about game design that summarizes the contrast between the perceived simplicity of implementing a trivial feature and the actual difficult nature of the task that becomes more apparent in a development process. The term was coined in 2014 by Liz England, a game designer, while she was working for Insomniac Games.[1][2][3]
The door problem originally models the difficulty of game development, but its core principle can be applied to many disciplines and areas of work.