Top of the list, I think, is... just some old-school D&D. Technically, probably Old-Shool Essentials or Dolmenwood, both of which are retroclones of B/X D&D.
I just got into watching Dungeon Meshi and playing Caves of Qud, both of which are just dripping with old-school D&D influence. Plus I've never actually ran a full dungeon or hex crawl.
Honorable mention to Burning Wheel, 16-time annual winner of My Favorite Game I've Never Played. :P