In the Shadow of Mount Rotten includes a couple of pages on random caves: odds of them occurring, sizes and shapes that simulate what actually happens in nature, water and minerals to be found, etc. Using those tools takes dice, paper, and a bit of time. For just a random cave, there are various generators online. I was fooling around with this one, which has pretty good output for tabletopping:
Now, what I realized is that these cave walls are random walks, creating a kind of pseudo-fractal effect… like a coastline. Set cave density to Highest, background to Plain White, entrances to Four: It’s a map of a world’s continents. A few changes and you have a fjord, or an archipelago.
Anyway. That’s gaming: Using the part of the brain that really makes us human to find story in random outcomes.