Wasn't No Shave November the movement that was supposed to bring cancer awareness?

I think OP is talking about the kind of lore deep dive videos, not necessarily the normal gameplay "Let's Play" style videos.

Has reddit actually been reopening subs? Seems like r/videos would have been their first target, but that's still private.

There is a similar game that recently came out called Humanity. It's missing a lot of the charm of the old Lemmings, but it's spiritually in the right place.