"Чего интересного" - why genitive?

Question

I was watching a video, and in it, the girl asked, "Что интересного произошло для вас в этом году?" Why is genitive bring used here? I have another example: Много чего интересного. Can что in a sense be translated as "thing"? I often see что/чего being translated as " thing". But I often see что being replaced with чего for no reason! Can the genitive be used as almost an "abstract subject"? I hope you understand my question.

Answer 1

'Чего' rather refers to 'много' here than to 'интересного'. The colloquial set expression 'много чего (такого)' basically means 'many such things (one could ask of or be interested in - too many to name all of them or to answer completely)'.

-Что происходило в городе в этом году?

-Много чего. (many things)

or:

-Что важного, интересного или неожиданного было в этом году?

-Много чего такого. (plenty of that kind)

So the genitive case of 'что' is adjusted for usage with the numeral 'много' (a noun in the place of this pronoun would have the same case). In your example the answer means 'many interesting things', with a flavour: too many for a simple answer.

Answer 2

I often see что being replaced with чего for no reason!

Generally, it is often used in informal language, I doubt you would see that in any kind of official text.