1
The character Colonel Claus Von Stiffenberg is named in reference to Claus von Stauffenberg, a German army officer most famous for his failed assassination attempt of Adolf Hitler on July 20, 1944. Similarly, the speech that he gives as the Zombies declare war on the other factions is a reference to "Ich bin ein Berliner" (translated to "I am a Berliner"), a speech given by U.S. President John F. Kennedy during the Cold War, specifically the line "All free men, wherever they may live, are citizens of Berlin, and therefore, as a free man, I take pride in the words "Ich bin ein Berliner!"".
person chocolatejr9 calendar_month June 23, 2024
Introduction in game (timestamp 28:39):
https://www.youtube.com/watch?v=sjcsflt8IHo#t=1719s

Timeline of Stauffenberg's life (note that source is in German):
http://www.dhm.de/lemo/html/biografien/StauffenbergClaus/

Archive of Kennedy's speech:
https://americanrhetoric.com/speeches/jfkberliner.html
2
The character Commandant SixFour is named in reference to the Commodore 64, the console where the first video game based on Risk was released on. This is alluded to in the game's Campaign Mode, where it's shown that Commandant SixFour uses outdated visual technology reminiscent of the Commodore 64's graphics, which leads to him Spoiler:betraying General McGutterpants shortly after activating, as he cannot tell the difference between the Humans and the Cats, thus declaring war on both.
person chocolatejr9 calendar_month June 12, 2024

Related Games