Game engines are a vital part of a game production pipeline, but there is a vagueness of definitions regarding the boundaries of components in a game engine and the rest of the production tools used in a game development pipeline. The aim of this paper is to nuance the use of the term game engine and to put it into the context of a game development pipeline. Based on data from the current state of game production, a proposed taxonomy for tools in game development is presented. A distinction is made between user facing tools and product facing tools. A defining characteristic of the production pipeline and game engines is their plasticity. One of the conclusions is that a “game engine” as a single entity containing the whole game production ...