Game engines are continuously evolving toolkits that assist in communicating with underlying frameworks and APIs for rendering, audio and interfacing. A game engine core functionality is its collection of libraries and user interface used to assist a developer in creating an artifact that can render and play sounds seamlessly, while handling collisions, updating physics, and processing AI and player inputs in a live and continuous looping mechanism.

Game engines support scripting functionality through, e.g. C# in Unity and Blueprints in Unreal, making them accessible to wide audiences of non-specialists. Some game companies modify engines for a game until they become bespoke, e.g. the creation of star citizen which was being created using Amazon’s Lumebryard until the game engine was modified enough for them to claim it as the bespoke “Star Engine”. On the opposite side of the spectrum, a game engine such as Frostbite which specialised in dynamic destruction, bipedal first person animation and online multiplayer, was refactored into a versatile engine used for many different types of games.