Rot.js
ROguelike Toolkit
Nipplejs
A virtual joystick for touch capable interfaces.
Panda.js
Panda.js HTML5 game engine
Limejs
HTML5 game framework for web and iOS
Cutjs
Lightweight, fast, interactable 2D HTML5 rendering engine for cross-platform game development.
Gamejs
GameJs is a thin library on top of the HTML canvas element. In addition to the drawing functions it has a set of generally helpful modules for game development.
Verlet JS
A simple Verlet physics engine written in javascript
Isometric
JSIso - An HTML5 Canvas Tile Engine
Flash JS
JavaScript graphics and games engine with API familiar to Flash one. Just look to examples sources.
Turbulenz Engine
Turbulenz is a modular 3D and 2D game framework for making HTML5 powered games for browsers and mobile devices.
Phina.js
phina.js is game library
Joy.js
A Joyful 2D HTML5 Game Engine.
Canvas Engine
Framework for HTML5 Canvas oriented 2D video games
Frozen
Frozen is an open-source HTML5 game engine delivering ease-of-use, rapid development through tooling and modularity.
Keydrown
A JavaScript key state handler for web apps
Enchant.js
A simple JavaScript framework for creating games and apps
Blend4 Web
Blend4Web is a tool for interactive 3D visualization on the Internet