Regarding D&D -- I guess it depends on what D&D Gen Z is nostalgic for. TSR-era D&D was mostly created by younger Greatest Generation types like Gygax, Arneson, Holmes, and Cook (Zeb), but definitely popularized by a lot of later boomers and Xers (the 'schoolkids' that Gygax didn't expect in his wargame spinoff). WotC D&D started with one boomer (Williams) and a bunch of Xers -- Cook (Monte), Tweet, Noonan, Redman, etc. and went on from there. Who was the bread and butter of the early WotC gamerdom seems to by something people seem to fight over (at least that one survey that didn't include certain generations caused quite a stir), but if Gen Z is nostalgic for it, I guess they were part of the crcrowd.