Umm i'm not sure what it means and i can't be bothered googling since if i could just google everything then there would be no point in me going on a forum.
I know a band that might fit into this category. I think they are screamo, i can't remember i haven't heard them in a while but all the music they sing to are like Mario theme songs, Zelda theme songs etc.
So is that what this chiptune means? That people have a band where the instrumentals is just video game music?