The first thought that comes right after someone mentions „alt art” is the game art. Suddenly, pixelated Mario becomes quite real in his plumber suit, posing like a dictator, koopas about and bombs flying overhead. It seems that alt art has become something like a keyword for all sort of playing with original popular culture icons like Mario, Sonic and the like. It doesn't limit itself only to games, but takes other old-school icons into account, like Scooby-Doo or Simpsons, always merging the existent content with new ideas and playing with conventions. In any case of this type, the keyword is always “alt art”.
I'll write more about this one soon.