These rating systems have also been used to voluntarily restrict sales of certain video games by stores , such as the German retailer Kaufhof 's removal of all video games rated 18 + by the USK following the Winnenden school shooting .
It is similar to the film rating system .
It is similar to the film rating system .
Simplificación: These rating systems have also been used to voluntarily restrict sales of certain video games by stores , such as the German retailer Kaufhof 's removal of all video games rated 18 + by the USK following the Winnenden school shooting . Producción: