Irrlicht is an open-source game engine written in C++. It is cross-platform, officially running on Windows, macOS, Linux and Windows CE and due to its open nature ports to other systems are available, including FreeBSD, Xbox, PlayStation Portable, Symbian, iPhone, AmigaOS 4, Sailfish OS via a QT/Qml wrapper, and Google Native Client.

A game engine is a software framework primarily designed for the development of video games and generally includes relevant libraries and support programs such as a level editor. The "engine" terminology is akin to the term "software engine" used more widely in the software industry.