I was playing the "very" historically accurate game Age of Empire 2 and while playing the campaign of a man named Fredrick Barborssa one of the maps entails defeating the "antipope" who is this ? Is the antipope like the arch enemy of the Pope and why would Barborssa fight him. Sorry if this is a dumb question.
An anti-Pope (there were many) is basically just any person who makes a somewhat accepted claim to be the Pope who is not the person generally accepted as pope, then they are an anti-pope. So, if I said I was the pope and got a ton of people to believe that I was the pope, then I would be an antipope