Well, nothing new has been invented since checkers, if you really think about it hard enough and reduce everything to a few buckets of games that everything can fit neatly into, then everything is just a mystery game or just open world or just a platformer. Again, I have a feeling like you're just looking at it mechanically and not how these elements work together to produce a game that is larger than just the sum of its parts. Outer Wilds has puzzles and open world and mystery element to it - and all of those have been done before. But has anyone else combined them this way to produce a game with this narrative? No, I don't believe so(happy to be proven wrong, as always).

Like the other commenter said - I hope I don't become jaded like this about video games, it still brings me joy to see how every new game twists the known formula a little bit more and in new and exciting ways, I believe there are several nieches where we haven't seen the game of that genre yet and I can't wait to see it emerge and how and who is going to do it.