Because of German laws — and Nintendo of Europe is based in Germany — 18+ rated games on the Wii U eShop in Europe will only be available after 11 PM at night. German youth protection regulations forbid the sales of 18+ / adult material until after 11 PM. Germany is famous for its censorship and crackdown on video games and media, so it’s of no surprise that they are going to such lengths to “protect the youth”.
The 18+ rated content will only be available from 11 PM to 3 AM at night, and this goes for all territories in Europe. For example, you won’t be able to download games such as ZombiU or Assassin’s Creed 3, unless you’re willing to stay up very late at night.
Luckily, this doesn’t affect gamers in North America.