Crystal Entity Layer is a framework for developing 3D games written in C++ by Jorrit Tyberghein and others. It is an extension of the Crystal Space 3D Engine. Crystal Space is itself not game-specific but Crystal Entity Layer adds game specific concepts and also the notion of game entities. Just like Crystal Space, Crystal Entity Layer is very portable and runs on Microsoft Windows, Linux, UNIX, and MacOS. Crystal Entity Layer is also open source, licensed under LGPL.
