Remove "Indie" as a genre
According to contribution guidelines, "Genre is the first tier in our 3-tier categorization system. Choose the most fitting genre(s) to broadly describe the game."
"Indie" is not the primary, broad description for a game. Maybe in 2007, but not today. They are puzzles/platformers/etc before they are indie. Indie is better suited as a keyword, if anything.
There are games which don't fit any other genres, and are purely experimental indie games. The indie game should be preserved for these games.
The problem is just like you said: the term is overused, and applied to games which fall into other genres. But there are some games which can't be described any other way.
a good example would be Click the Clown 2020. (https://hubol.itch.io/click-the-clown-2020).
AdminIGDB (Admin, Twitch) commented
This is taken directly from our Contribution Guidelines, under Categorization.
We do have a revamp of our Themes/Genres/Keyword feature, it's a large undertaking that needs planning and is in the ideation phase at the moment. Expect to hear more!
Where did you read about the 3-tier categorization system? I tried looking it up the block you quoted on Google, but only found a link to your comment.