As kids we definitely fought the “Japs” (as they were universally known then)during our war games; the cry being “Bombs over Tokyo!” Ordinary Krauts not so much; instead, Hitler was the personification of Germany.
You can't compare the moral plane of American kids playing war games targeting Japs or Germans, on the one hand, and German kids playing "Get the Jews out," or whatever it translates into, on the other.
Japan's vicious sneak attack on Pearl Harbor killed about 2,500 Americans and forced the US to enter a war for its very survival. Before it was over, something like 440,000 American servicemen had been killed primarily by Japs and Germans, and many an American kid never got to see his father come home alive.
By contrast, not a single German Jew or other European Jew had killed massive numbers of Germans at the time that sicko anti-Semitic children's board game was invented. Jews were merely targeted for what was eventually mass murder by the Nazis' perverse ideology dreamed up and executed by an evil totalitarian regime.
BTW, as the child of a WWII vet, I don't think there's anything unbecoming to use the word "Jap" when discussing the history of WWII.