SDL
From Mario Fan Games Galaxy Wiki
SDL, or Simple DirectMedia Layer, is a cross-platform, open-source library programmed in C. It provides various pre-programmed functions related to graphics, audio, input, and more. By design, a program written using SDL can be compiled on nearly any platform, including non-PC platforms.
C and C++ are used directly with SDL, but it also provides various bindings to other languages, such as C# or Java, or scripting languages like Python and Lua.
On Windows, it uses DirectX, while on Unix-like Systems, it uses the X Window System.