Old School informed GURPS Dungeon Fantasy gaming. Basically killing owlbears and taking their stuff, but with 3d6.
I remember the Roman d20. This one is awesome. Looks amazingly well crafted / sharp. Zocchi must have Egyptian ancestors.
There's a Greek d20 in the British Museum, though I can't find a photo on-line. It's about 3" across and has fairly curved edges.