Raylib

I've covered programs designed with lightweight GUIs and text user interface libraries such as SDL, FLTK and pdcurses in previous posts. Another interesting and promising cross-platform lightweight screen library is raylib. There's a GUI for it called raygui. There's even a cross-platform audio library called raudio. Programs written with raylib have been ported to several computers including Linux, Windows and Mac. It can be used to write programs for mobile devices. The audio library works on multiple platforms including mobile devices as well.

You can find raylib and several helpful libraries you can use with it at:
https://github.com/raysan5

I haven't had a chance to check out many of the programs that are built with raylib. However, you can find a group of example games at:
https://github.com/raysan5/raylib-games
I've been trying to find a decent jigsaw puzzle game written in C. There is a photo puzzle game for raylib at:
https://github.com/klaytonkowalski/game-photo-puzzle

There's also an experimental GUI editor here:
https://github.com/Demizdor/experimental-raygui-editor

I'll add other interesting raylib examples as I find them. Feel free to share you're own as well.