To get your app into the Windows Store it needs to meet requirements and be certified, you also need a developer license.
Developer licenses are free, you can have as many as you need if have a Microsoft account and these must be renewed every 30 days. To get a 90 day developer license you need a windows store account.
To have your app accepted for the windows store you need to package it and get it certified. If the windows store hasn’t certified the app it can’t run on windows unless you have a developer license installed on the local machine, or was sideloaded via your 'enterprise' which is available in in Windows 8, this restriction doesn’t apply to desktop apps.
To have the app certified; You must install and run (now) Windows 8, have the (now) latest version of the Windows App Certification Kit installed (included in windows 8 SDK), have a valid developer license for your computer, deploy the proposed windows store app that you want to test to your computer. Certification testing is always with the latest OS and SDK installed. Apps previously certified (for Windows 7 this was known as the Windows Software Logo Program) for a previous OS don't need to be re-certified generally unless intended to also run in the latest OS (Windows 8 in this case), if you intended for previously certified to run in the latest OS version then it needs to be certified for that OS and the latest is Windows 8 so in this case they would also need to meet the Windows 8 level of certification.
The certification testing is based on the performance of a low power computer. Details, instructions, and information for the certification test can be found here >
http://msdn.microsoft.com/en-us/library ... 94081.aspx
More information ; >
http://msdn.microsoft.com/en-us/library ... p/hh749939 (its not a requirement of certification a desktop app use the (formally known as) 'metro' UI for certification or .net (but C# or C++ is preferred, a visual basic type language can't be used), but it depends on other factors.
After certification, the app still has to pass review and 'certification' by the MS people who run the windows store so its still possible for an app to pass the certification yet be rejected for the windows store due to various things but that's another story.
PureBasic based apps will (most likely) not pass certification or meet acceptance parameters/requirements in various aspects.
(games and apps are considered synonymous for most purposes in this context i'm advised by our MS rep here)