Citizen Kane changed the way films were made. People point to the movie as the moment films moved from being filmed stage productions to what we saw in films over the past 60 years.
If we were looking at gaming's
Citizen Kane, it would have to create seismic changes in the way games are made. I'm looking forward to Last of Us, but I don't expect that.
If you want to know more about Citizen Kane and how it led to Orson Welles's demise as a filmmaker, you can see it here.
He was blackballed from the movie industry, because Citizen Kane was basically opening a window to the eccentricity and controversy surrounding William Randolph Heart's life. Hearst owned the papers and used his connections with the media and government to write terrible things about Welles, prevent him from winning an Oscar, and try to have the government blacklist him as a communist.
Here is the first part.
https://www.youtube.com/watch?v=rR2s6_Xbi9M