WADE - The easiest 2D and isometric HTML5 engine to make amazing web games and apps. Free and open source.

WebGL - WebGL is a JavaScript API for rendering interactive 3D computer graphics and 2D graphics within any compatible web browser.

SFML - SFML provides a simple interface to the various components of your PC, to ease the development of games and multimedia applications. It is composed of five modules: system, window, graphics, audio and network.

Vulkan - Vulkan is a new generation graphics and compute API that provides high-efficiency, cross-platform access to modern GPUs used in a wide variety of devices from PCs and consoles to mobile phones and embedded platforms.

Allegro - Allegro 4 and Allegro 5 are cross-platform, libraries mainly aimed at video game and multimedia...

CrossBrowdy - Open-source JavaScript framework to create cross-platform and hybrid game engines, games, emulators, multimedia libraries and apps