I've realised my "game shelf" app idea was implemented very well by https://backloggd.com/

Users can make lists, with a note for each game, and share them publicly. When you view a list you can see which games are in your backlog or that you've played.

The only thing missing (a big one!) is Steam integration, so you can see what's in your library or wishlist, your progress, hours plsyed, etc.

Without some form of auto-sync adding all my games is just too laborious.