SDL - Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level...
wxWidgets - wxWidgets: Cross-Platform GUI Library
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Electron - Build cross platform desktop apps with web technologies
Unity - The multiplatform game creation tools for everyone.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.