Bennu is a high level open source game development suite which focuses on modularity and portability, making it a perfect choice for cross-platform game development.
Although officialy it is only supported on Windows and Linux, Bennu can run on multiple other platforms, including *BSD, MacOSX and consoles such as GP2X, and Wii.
Bennu -which was born as a Fenix fork- is actively mantained and makes it easy for both beginners and experienced users to create their own games.