Microsoft will soon start selling M-rated games in the Windows Store, Gizmodo confirms. The virtual storefront which launches alongside Windows 8 today was hobbled pre-launch when Microsoft revealed content guidelines that would effectively prevent some of the gaming world's most popular titles, including the company's own Halo 4, from being sold there.
The problem arose as a result of the ratings system differences in the U.S. and Europe. Our own ESRB has separate M and AO ratings; the former is a common sight on game store shelves while the latter is usually reserved for racy material (and highly controversial Rockstar releases). In Europe, the PEGI 18 rating governs both categories. Ultimately, you can't buy Call of Duty from the Windows Store because of what amounts to a policy hiccup.
Microsoft is aware of the issue, but you won't see any immediate changes to the storefront. M-rated content is expected to be available in the Windows Store before the end of 2012.