Crystal Space is an Open Source and portable 3D Engine Framework. It is a strong and active project with many side projects (like Crystal Entity Layer and AresEd game editor). Crystal Space is very powerful, extensible and flexible. It uses OpenGL for rendering and supports advanced features like CG shaders, skeletal animation with ragdoll, support for physics using bullet or ODE, 3D sound using OpenAL, terrain engine, particle systems, and a lot more. Crystal Space is written in C++ but has high quality bindings for Python even allowing the creation of full 3D applications in this language.