The general strategy always is to get something working
first and then improve.
This is NOT the top-down approach one might ideally want, but
an initial solution often gives insight into a later one.


So, for a single snowwalker, that's some kind of spiral pattern.

For two, that's a grid.

For more than two, maybe work from several sides of the grid.
Then use a heuristic technique like simulate annealing (or in this case
genetic algorithms) to improve it.