FlightGear Flight Simulator: free open-source multiplatform flight sim
3D Engine c++
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
A Realistic and Rich 3D Environment
3D .NET engine for Windows, Linux, Mac
action/combat flight sim
A cross-platform game framework based on OpenGL and GObject.
A continuation of the abandoned Tao Framework project.
Multi-Language Wrapper Collection for the Irrlicht Engine
Volume Rendering library in Java