Creating a game for Windows 8 is easy with Construct 2. If you haven't already, download the Free edition and get going with the Beginner's guide!
Note: consider publishing a Universal store app, which also supports Windows Phone 8.1+! Find out more by reading How to export Windows Store apps. The rest of this tutorial will cover Windows 8.0/8.1 only, without phone support.
Setup
You'll need Windows 8.0 or 8.1. You then need to install Visual Studio 2012 Express for Windows if you plan to make a Windows 8.0 app, or Visual Studio 2013 Express for Windows if you plan to make a Windows 8.1 app. Both are free downloads and can be found on the Visual Studio downloads site.
We recommend exporting for Windows 8.1 - it's the latest update, is available for free to Windows 8.0 users, and uses IE11 instead of IE10 as the browser engine which adds new features like WebGL support.
Development
You'll need to add touch controls. See this tutorial on touch controls for help on that.
Different devices have different size screens. See supporting multiple screen sizes.
You can add the Windows 8 object to your project to take integrate with Windows 8 specific features like in-app purchases.
Exporting from Construct 2
First, ensure your project has the right Name, Description and Author properties set, since these will be used in the exported app.
In the Export Project dialog, choose Export for Windows 8 and follow the next steps as you would for exporting an ordinary project. You'll also have the option to choose between exporting a Windows 8.0 app (using Visual Studio 2012) or a Windows 8.1 app (using Visual Studio 2013).
In the export directory you will find a Visual Studio project. Note there are three image files for the app icons, app-logo.png, app-smalllogo.png and app-storelogo.png. You should replace these with your own images but keep them exactly the same dimensions.
The main project file has the extension .sln (solution). Double-click it and Visual Studio should open it.
Testing from Visual Studio
If you've not used Visual Studio before, it's a complex and sophisticated tool for application development. However, you only need to use a small number of commands to configure and test your app. Find the "Solution Explorer" bar which lists all the files in the project.
Double-click package.appxmanifest. This file contains all the settings for your app. There is one thing you need to set up because Construct 2 can't export it for you, which is the publisher certificate for your app. Click the Packaging tab, which probably has a red X by it because the certificate is not set.
Now click Choose Certificate.... In the dialog that opens, click the dropdown and select Create test certificate....
A dialog appears with your Publisher ID and a password entry. Don't enter a password - leave it blank and hit OK. Click OK on the Choose Certificate dialog as well, and you should now have a certificate set (mine appeared as CN=Ashley). If you've done this correctly the red X should have disappeared too.
Test certificates only allow you to test your app. When publishing to the Windows 8 App Store, you'll need a different certificate to publish your app.
Now you can launch your app by pressing F5. Visual Studio will build it and launch it as a Windows Store app, which uses the Internet Explorer 10 browsing engine on Windows 8.0 or Internet Explorer 11 on Windows 8.1. This allows you to test everything is working in the new browser and OS. You can also try tweaking the settings in package.appxmanifest, which include options like orientation lock and other tile images.
Publishing
To submit to the Windows Store, start following the steps from this URL:
https://appdev.microsoft.com/StorePortals/
You may need to pay a fee to open a new Microsoft Developer account. The website will take you through all the necessary steps and provide the publishing dashboard from where you can publish apps to the Store.
You may also be interested in Henry Hoffman's tutorial on how to add in-app purchases to Windows 8 games.
Other options
See also:
How to make a Windows Phone 8 app
How to make Android games
How to make iPhone and iPad games
How to make an iOS web app
Publishing and promoting your Construct 2 game