Kiwi.js aims to be 'the Wordpress of HTML5 game engines'
: A new open-source mobile-first HTML5 game engine launched today, with support for both WebGL and Canvas rendering, and CocoonJS for boosted performance.
Kiwi.js is a game engine from the GameLab team in New Zealand, with the aim to be "the Wordpress of HTML5 game engines." It comes with plugins, game templates and documentation to support developers.
The engine is currently open sourced under the MIT license, but it has clients using it commercially. You can download the engine at the official website