HoS: What Made it Fun?

Let's talk about what has gone really well in my five-session Houses of Stone game.
Quick recap of essential info if you didn't play:
- Swords & Wizardry Core rules (mostly)
- Sub-Saharan Africa in an alternate timeline
- History coming out the ears of every NPC, location, and item

I have run five sessions of this game so far, and enjoyed every one, and I believe the players did, as well. The first and foremost thing I think we all enjoyed was history.
The history in this world--the things the PCs had no knowledge of but uncovered by role-playing interactions with NPCs, by exploring locations, by investigating events, by inquiring about items and events--was pretty well laid out, if I do say so myself.
We only really "delved" into dungeons/caves in two of the sessions. Even then, though, only one was a real delve, where the PCs spent almost the entire session exploring the turns and twists of the underground complex. The very first session had about 45% of the time spent in the dungeon, but with a considerable amount of investigation and interaction happening before and after, arguably being the more enjoyable part of the game.
So, my point is, I think the players enjoyed learning by exploring, inquiring, and investigating what the history of the world was.

Second, I think everyone enjoyed puzzling items and contraptions. The simplest things, like a panel of buttons on a purely granite wall in an iron age world, activated by the Fibonacci sequence, was incredibly fun to see players work through.
The puzzles and contraptions, too, contribute to the history-delving of the world. Even though these are classic dungeon puzzles/traps/contraptions/conventions, they played right into the mystery of the ancient race who built the city.