In Europe, you can only download 18-rated games between 11pm and 3am. The reason for this? Because Nintendo Europe is based in Germany and therefore has to abide by German law which doesn't allow for 18-rated content to be made available during the day.
"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," a spokesperson told CVG.
"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."
ZombiU is now available (well it isn't if you're reading this before 11pm, but you know what we mean) for £54.99 from the Wii U eShop.