One worth mentioning is the Thieves’ World series first edited by Robert Lynn Asprin. The early books were anthologies of short stories by various SF&F authors. They were all set in the same universe, and centered on the city of Sanctuary.
It was fascinating to see how different writers approached storytelling in a shared universe. I recall one writer being ticked-off when another writer killed off a fan-favorite character.
I think this could work well with IF: A shared world with a basic map and outline, and various writers filling out the framework with their own games. It could even be assembled as a jam. (Now that I write that, I bet there was a jam like this at some point.)
(Disclaimer: I’m not the first to suggest this. Other mentions include this thread from 2012 and this post from last year.)
Addendum: I’m aware of games such as Cragne Manor and Pick Up the Phone Booth and Aisle and like. I’m speaking of a broader, looser collaboration, with many games tied together by location and common history.