Allegro is a free and popular game programming library. Originally written for the DOS platform, the Allegro API has been ported over to other platforms such as X Windows and Win32. Allegro supports a variety of graphics modes, animation data formats, GUI management procedures, MIDI playback, and mouse, keyboard, & joystick support.

Simple DirectMedia Layer is a cross-platform multimedia library designed to provide fast access to the graphics framebuffer and audio device. It is used by MPEG playback software, emulators, and many popular games, including the award winning Linux port of "Civilization: Call To Power." Simple DirectMedia Layer supports Linux, Win32, BeOS, MacOS, Solaris, IRIX, and FreeBSD.

SDL is written in C, but works with C++ natively, and has bindings to several other languages, including Ada, Eiffel, ML, Perl, PHP, Python, and Ruby.

It was created by Loki Software so that they could make their games available on a variety of platforms including Linux. It is freely available open source and is licensed under the LGPL.