Granted, if you are writing a game and can sell it through Steam, you'll probably do ok, but Steam as a distribution platform still pales in comparison to the potential reach of the Windows Store.
Minus the restrictions in the Windows store...
5. Windows Store apps are appropriate for a global audience
This section describes types of content that are not permitted in the apps made available in the Windows Store.
Content means the images, sounds, and text contained in the app, the tiles, notifications, error messages or ads exposed through your app, and anything that’s delivered from a server or that the app connects to. Because Windows and the apps in the Windows Store are used around the world, these requirements will be interpreted and applied in the context of regional and cultural norms.
5.1 Your app must not contain adult content, and metadata must be appropriate for everyone
Apps with a rating over PEGI 16, ESRB MATURE, or that contain content that would warrant such a rating, are not allowed. Metadata and other content you submit to accompany your app may contain only content that would merit a rating of PEGI 12, ESRB EVERYONE, or Windows Store 12+, or lower.
We understand that in some cases, apps provide a gateway to retail content, user generated content, or web based content. We classify those apps as either Storefront apps, whose primary function is to aggregate and sell third party media or apps, or Streaming apps, whose primary function is to aggregate and stream web-based images, music, video or other media content. In some cases, it may be acceptable for a Storefront or Streaming app to include some content that might otherwise be prohibited in a single purpose app.
5.2 Your app must not contain content that advocates discrimination, hatred, or violence based on membership in a particular racial, ethnic, national, linguistic, religious, or other social group, or based on a person’s gender, age, or sexual orientation
5.3 Your app must not contain content or functionality that encourages, facilitates or glamorizes illegal activity
5.4 Your app must not contain or display content that a reasonable person would consider to be obscene
5.5 Your app must not contain content that is defamatory, libelous or slanderous, or threatening
5.6 Your app must not contain content that encourages, facilitates or glamorizes excessive or irresponsible use of alcohol or tobacco products, drugs or weapons
5.7 Your app must not contain content that encourages, facilitates or glamorizes extreme or gratuitous violence, human rights violations, or the creation or use of weapons against a person or animal in the real world
5.8 Your app must not contain excessive or gratuitous profanity
http://msdn.microsoft.com/en-us/library/windows/apps/hh694083.aspx
Have fun with Angry Birds...