You won't be able to buy PEGI 18 games on Windows Store which means nearly all of the biggest and best games released in the past three years can't be bought in Europe and other markets.
For the United States, that's not exactly an issue. Not many major video games ever receive a rating beyond "Mature", the only notable exceptions being the PC version of Manhunt 2, the Director's Cut of Indigo Prophecy and, during the "Hot Coffee" scandal, Grand Theft Auto San Andreas.
But for other markets, it's a bit of a disaster. Europe especially. Here are some games that have, only recently, been awarded Europe's PEGI 18 rating, which under Microsoft's rules would mean they'd be excluded from the Windows 8 marketplace:
- The Elder Scrolls V: Skyrim
- The Witcher II
- Call of Duty: Modern Warfare 3
- Max Payne 3
- The Walking Dead
- Sleeping Dogs
- Dishonored
- Mass Effect 2
- Mass Effect 3
- LA Noire
- Spec Ops: The Line
- Fallout: New Vegas
- Deus Ex
- Assassin's Creed: Revelations
Source: Kotaku