WebGL offers new very interesting opportunities for the gaming industry.
You can now develop a game for the web running cross-platforms and take the very same code to build a Windows Store App and add some platforms specifics & monetization.
Pre-requisites: validate your game in IE11 which now supports WebGL
Step 1. Validate your code against Internet Explorer 11.
To test against IE11, the best experience is to install any version of Windows 8.1 on a development machine. IE11 is also now available on Windows 7.
You can also test it as a first experience via Virtual Machines or via BrowserStack or bootcamp, parallels on Mac.
If you dont have access to MSDN or a copy of Windows 8 You can find free VMs to download on our Modern.IE website: http://www.modern.ie/en-us as well as a 3-months trial for BrowserStack.
Of course, especially for a game, you will have to test at the end on real device to tune the performance and the gameplay.
Step 2. Be sure that your game runs in every WebGL-enabled browser/platform.
Doing these two tasks will save you some time in the future and maximize your reach.
So what is new with IE11
IE11 embeds the JS & rendering engines being used to execute Windows Store Apps. So, when you’re writing HTML5 Windows 8.1 Store Apps, you’re more or less targeting IE11.
Using a WebGL engine
I would strongly suggest using a WebGl engine rather than writing yourself your code against the low-level API of WebGL.
Any WebGL engine working fine in Internet Explorer 11 but here a two excellent opensource options.
There are lots of resources available to learn ThreeJS
Open-source WebGL engine specifically designed for creating games.
Babylon.JS is scene oriented and has a great Blender exporter.
Using Web Application Template
For Games with WebGL. A nice way to get these to WP8 and W8 is the web app template. http://wat-docs.azurewebsites.net/
You can also relatively easily add xbox controller, sound etc.. using Xinput control feature of Windows 8
Please watch the videos below demonstrating the use of the Web Application Template (WAT) being used to build a Windows 8 HTML5/JS game.
The game can also be built as a native Windows 8 game the advantage this had over the WAT was the game could work offline.
Here is a recording of the endeavours and this 10 minute video shows how you would technically go about porting a game like this using both the WAT approach and the native approach.
The native implementation 6:40 seconds in : https://youtu.be/T51tgL3qzi8?t=6m40s
If you just want to see the app running then check out 5.42 minutes in https://youtu.be/T51tgL3qzi8?t=5m24s
For more details of the Web Application Template see msft.it/60119JW9