SDL
From Agar
Simple DirectMedia Layer (SDL) is a cross-platform multimedia library which provides a unified interface to graphics hardware, sound hardware and input devices across different operating systems.
Agar's direct video rendering mode uses SDL to access the video display, and SDL's input device interface to generate GUI events. On platforms featuring hardware graphics acceleration, OpenGL is mode recommended over SDL, since frame-buffer rendering requires expensive graphics operations to be performed by the CPU.
Thanks to SDL, Agar runs on a wide array of operating systems and graphics interfaces.
