I'm not sure if you're being sarcastic about the "something silly" part, but do you have any examples of any games (indie, commercial or academic) that let you meaningfully impact the game world?

I think they don't exist because it's an exceptionally difficult problem, even for games with lo-fi graphics or text only. I've found it hard to find any AI projects that generate stories or plots that are remotely compelling.

Big studio game companies push "your choices matter" as a selling point as well, but few deliver.