A full 3D open source game engine that you can toy around with. If you have been dying to try out your game rendering skill but don’t want to spend tons of cash getting commercial software for it, then Panda 3D could help you in that department. Panda 3D is a free open source game engine that can help you with all your basic game rendering needs.
The software was originally run and developed by Walt Disney VR Studio while additional developments were put in by Carnegie Mellon University for the open source version. Panda 3D works great in cutting back cost and fulfilling game projects at a relatively faster pace.
Apart from the fact that it is offered for free under a liberal license, Panda 3D is an extremely easy and versatile game engine to work with. It drastically minimizes the learning curve of first time users and helps them get down to the nitty gritty stuff.
The software provides you with various tools and features for game rendering. Here are some of the common tools you will get: shader generation which provides special maps, HDR rendering and cel shading; graphics API; Python integration  as well as 3D audio, just to name a few. It also provides extensive debugging tools to help prevent system crashes right when you are doing work. Performance monitoring also comes with the system which helps identify any bottlenecks in the CPU and GPU.
The software itself is commonly used by different game developers, both for personal or private use. There are also schools that ask students to use the program for creating various projects.
Related Links:
Panda 3D Official Website
Panda 3D on DevMaster
Panda 3D on Rbytes
Panda 3D on Linux Links