Over at the Hill Cantons blog, Chris has written a lot about the
pointcrawl, which abstracts a map to the important points, eliding the empty places/boring stuff a hexcrawl or similar complete mapping would give equal weight. One unusual variation not yet explored is the crawling of moving points.
Admittedly, these would be pretty unusual situations--but unusual situations are the sort of stuff adventures are made from: Exploring a flotilla of ancient airships or the various "worlds" in a titan wizards orrery; Crawling the strange shantytown distributed over the backs of giant, migrating, terrapin. Flitting from tiny world to tiny world in a
Little Prince-esque planetary system. Some of these sort of situations might stretch the definition of pointcrawl, admittedly, and to model some of them in any way accurately would require graphing or calculus, and likely both.
Let's take a simple case--something from
an adventure I'm working on. Say the wrecks of several ships are trapped in a Sargasso Sea of sorts. The weed is stretchy to a degree, so the wrecks move to a degree with the movement of the ocean, but the never come completely apart.
The assumption (to make it a pointcrawl, rather than just a hexcrawl, where the points of interest move) is that there were pretty much only certain clearer channels a small boat could take through the weed--or maybe certain heavier areas that a person who wasn't too heavy could walk over without sinking in complete.
The map would look something like this:
Note that this map is pretty abstract, despite appearances. The distances or size of the weed patch aren't necessarily to scale with the derelict icons. Length of connecting lines is of course, indicative of relative travel distance. The colors indicate how "stretchy" an area is: blue can move d4, orange d6, and red d8 in feet? yards? tens of feet? Not sure yet. Anyway, whether this drift is closer or farther away would depend on a separate roll of 1d6 where odds equals farther and evens closer. Of course, they can't come any closer than the distance they are away on the map, so any "extra" distance would be a shift to one side or the other.
Zigzags denote a precarious patch, where there would be an increased risk of a sudden thickening (if I'm going with boat travel) or falling in (if I go with walking). Dots will denote an extra wandering monster or unusual event check.
So there are a lot of kinks to work out, but that's the basic idea.