I feel like this would work even better as a daily game like Wordle with the same 5 pics for everyone to play so you can (lightly) compete with friends.
And at the end, you could get some trivia for each of the photos
The trivia thing was asked for at reddit too, but i looked into the file storage of the server and it seems that the photos are just plainly stolen from all over the internet with file names like chronophoto.app/years/1963/ap630629032-02fcaf4ca7736109b998d760283a3a9ba7bceda7-s900-c85.webp
or
chronophoto.app/years/2017/ed-jones-north-korea-top-100-photos-2017.jpg
No credit is given anywhere too. This is probably illegal and the author will get in a lot of trouble if he does not do something about that soon.
And at the end, you could get some trivia for each of the photos