Top 4 rendering-2d-graphics open source projects

The HTML5 Creation Engine: Create beautiful digital content with the fastest, most flexible 2D WebGL renderer.

Saddy is an open-source crossplatform 2D graphic engine, based on OpenGL, which can be used for creating 2D games. like platformers or RPGs.

Yet another 2D API abstraction

Vivid is a simple 2D rendering library written in Elixir.