|"Nazis! I Hate These Guys!"|
Few, if any, real world evils have generated quite as many far-out conspiracy theories as the Nazis, so here's a link to 10 of these eminently gameable claims, courtesy of Listverse.
Every one of these could serve, either individually or in combination, as seeds for adventures in multiple genres, from pulp gaming through superheroes (it wasn't just Captain America who fought them, you know) to sci-fi.
A tip of the battered fedora to Matthias Janßen in the Hollow Earth Expedition Explorers Facebook group for drawing this link to my attention in the first place.