That's not entirely correct. The games exist; otherwise, you wouldn't be able to activate keys for them and/or have friends abroad gift you games of this type on Steam. But it is possible!
This means that if you, as the developer, also offer to send keys to German players, then this would also be possible.
I'll get my hands on your game anyway, so I'd have a friend abroad buy it for me!
But I think you should know that it's definitely possible.
The developer of "Tame It!", for example, started a Kinguin sale specifically for his German fans. Other games like "Fantasy Brothel" also sent their keys to German players via Patreon, and they all work!
The problem with erotic games isn't that they're illegal in Germany, because they certainly are. The issue for German authorities on Steam lies more with the age restrictions on the store pages themselves. Trailers aren't allowed to contain pornographic content. Most erotic games do, of course, include pornographic material on their store pages, which is why these pages are blocked in Germany. The pages are blocked, but the games themselves, even if obtained via key or Steam gift, are not!
