Gosu
2D game development library for Ruby and C++
...It provides a window and a main loop. 2D graphics and text, powered by OpenGL or OpenGL ES. Sounds and music, keyboard, mouse, and gamepad input. Gosu is mostly used to teach or learn Ruby or in short game development competitions. It’s also a great prototyping tool and should work for indie game development, though nobody has really tried that. In addition to the documentation linked from the sidebar, there is a free book by Mark Sobkowicz that will guide you through the creation of four different games.