Tilengine is an open source, cross-platform 2D graphics engine in C for creating classic/retro games with tile maps, sprites and palettes. It’s intended use is for developing 2D games of old.

Written in C99, it can be used on Windows (32/64), Linux PC(32/64), Mac OS X and Raspberry Pi. Internally it uses some SDL2 libraries. There are bindings for other programming languages as well as native support for C/C++.

You’d use this for parallax effects using sprites over background layers. It makes it easier than coding yourself. In particular sprite animation is excellent with pixel perfect collision detection and 17 different functions for manipulating them. Rather than roll my own in my Asteroids game I could have used this.

The other documentation is a little spare with placeholders, but I imagine you can work it out from the header files and samples.