A survey of 165 children by researchers at the University of Regensburg discovered that games had fallen into the hands of at least seven. They include Concentration Camp Manager in which players have to decide whether Turks (the largest ethnic-minority group in Germany) should be put in labour camps or immediately gassed.
Another, entitled Achtung Nazi, is set at Auschwitz concentration camp and the aim of the game is to gas as many Jews as possible.
Helmut Lukesch, psychology professor at Regensburg, said the videos are easily copied and sent via electronic mail boxes. He said it was difficult to track down exactly who is distributing them.
He said: "The games are technically excellent quality and they cost nothing. The distributors have no commercial interests, only ideological ones. They build a world view with these games that children cannot protect themselves from."
The disclosure has come at a particularly sensitive time in a year of anniversaries commemorating the end of the Second World War. And it has fuelled the soul-searching debates in Germany about coming to terms with the past and the way children are educated about it.