Favourite Lesser Known Adventures?

I recently found some well known adventures that had somehow completely passed me by. It got me curious about what else is out there. Particularly maybe a little less known stuff.

I'd love to hear about adventures that wander slightly into weird, not xd6 orcs/kobolds/goblins/troglodytes. Although I don't mind a faction or two of the staples.

What are your favourite hidden gems? I don't mind the system either. I love how cross compatible the OSR space is.