As per title. I personally really enjoy deckbuilding / engine builders and civilisation games, but most of them understandably end just as you’re hitting the sweet spot of getting your engine up and running. Probably why Through the Ages is my favorite game - has all the mechanics I like, but lasts long enough that I feel like I get a chance to run them.
In card games I always like that little spice that’s added when discards can be picked up by someone else and used. It adds an element of “should I perhaps continue with this less-than-perfect hand, or should I risk helping someone else build the perfect hand?”
This is a huge part of Arboretum (do I discard this card I know you want or am I safe to discard this other card I might need), and also big part of Fantasy Realms
I don’t know these games (I’m out of the loop on commercial and board games for the past 20-odd years, sadly) but I have loved this mechanism since playing the earliest rummy-family games from China. (Majiang is the most recent of a loooooooooooooooooong line of build-and-discard games in China.) The added spice of worrying if someone is going to use your discard to improve their hand or even complete it before you can do yours is part of why I like playing the rummy family.
I recommend checking out Arboretum: https://youtu.be/mmiXSOG1BtQ
It’s a small box game (just a deck of cards) so not too expensive, and it really hits that “If I discard this someone else is going to want it.”