Thousands have been gathering in San Diego this week for Comic-Con International, America's biggest celebration of all things nerdy - not just comics, but movies, TV shows, novels and video games.

If it's sci-fi, fantasy or superhero-based, it's certain to be represented somewhere on the convention center's sprawling floor space.

SOUNDBITE, Brandon Paananen, saying:

"I think it's just the atmosphere really because everyone here is just as passionate and excited about the same stuff you are. "

SOUNDBITE, Carolyn Powell, sci-fi fan, saying:

"I think it's just the atmosphere and the excitement of getting to be nerdy and doing whatever you want without having to feel anxiety. ."

SOUNDBITE, Marco Rojas, sci-fi fan, saying:

"We're all geeks and nerds here. We can be here and be ourselves. ."

Stars from new sci-fi movie Ender's Game hit the red carpet at the convention.

Among them veteran actor Harrison Ford, revered by the Comic-Con audie