JavaScript - Lightweight, interpreted, object-oriented language with first-class functions
Pygame - Pygame is a set of Python modules designed for writing games.
Qt - Powerful, flexible and easy to use, Qt will help you not only meet your tight deadline, but also reduce the maintainable code by an astonishing percentage.
Unigine - Unigine Engine is a proprietary cross-platform middleware, developed by Unigine Corp.
Allegro - Allegro 4 and Allegro 5 are cross-platform, libraries mainly aimed at video game and multimedia...
libtwo - All-purpose c++ app prototyping library, focused towards live graphical apps and games