European Wii U owners accessing the Wii U eShop will only be able to view and purchase 18+ rated content between the hours of 11pm and 3am, Nintendo has confirmed to Eurogamer.
This means full titles such as ZombiU and Assassin's Creed 3 can only be purchased during this four-hour window.
Nintendo says the restrictions stem from German regulations applicable because Nintendo of Europe is based there.
"At Nintendo we always aim to provide a safe gaming experience for fans of all ages and ensure that we comply with applicable legal age restriction requirements across Europe," explained a Nintendo spokesperson.
"Legal age restriction requirements vary across a number of European countries. Since Nintendo of Europe is based in Germany, Nintendo eShop is complying with German youth protection regulation which therefore applies to all our European markets. Under German law, content rated 18+ must be made available only at night."