Running your Game
That is all of the changes that need to be done to the project to get it up and running. You will still have a few more changes to get it to actually pass the app store certification but those will be discussed later.
If you run the game using the default "Run with Debugging" which is the F5 key or the Green arrow you might find that it runs choppy. This is due to the Debugging part of that run. If you choose to "Run without Debugging" which is the CTRL-F5 key combination or the Green arrow with the clear middle you will find the game runs without the stuttering.
You might find that the app crashes during checks to Clay.io due to delays in how Windows 8 sends data to their servers or when using an offline device not even connecting at all. Using the Clayio.Ready and Clayio.Loggedin System Values in Construct 2 can help you make sure you only do your Clayio calls when you should make them.
You will want to go into the package.appxmanifest file to update the icons, descriptions, and anything else that is Windows 8 specific. You will need to redo all of these steps each time you want to test due to how Construct 2 exports the Windows 8 project. You might also run into an issue with the .js/.css files from Clay.io still being in the exported folder but not in the actual project if you export back into the same directory when doing a later build. If this is the case you should delete these files first before adding them back into the project or Visual Studio might throw a fit since the files exist already.
Things to do before publishing to the App Store
The most important thing to do before trying to get the app published is you need to update the privacy.html file in your project with a link or description of your privacy policy. This is a REQUIREMENT for all apps even if you do nothing and Microsoft will reject you flat out for not having it in the charms bar. Since your app will be using Clay.io and will be using personal data you might want to link to their privacy policy at http://clay.io/privacy to be safe.
Optional but certainly nice to update as well are the about.html and support.html files. These are good places to put information into your app about how to play the game as well as how to contact you for support.
Another issue you will run into is UTF8 encoding on the imported Clay.io files. If these are not changed they will cause a fail on the WACK test during certification. To do this open up file in Visual Studio and choose the Save File As.. Option. Choose the Drop down menu next to the Save button and choose Unicode (UTF-8 with signature) - Codepage 65001 option and hit OK.