I've been doing some work on my pathfinding system, and trying to come up with a good estimation of the cost of moving between neighboring tiles in my map, based on the height variance between tile centers. I've been using the slope between tiles as my measurement, but I've been having some difficulty determining the maximum walkable slope that should be allowed.
It's surprisingly hard to find good information on what the maximum walkable slope for a human is. Based on some guides for building hiking trails, like this, and guides on roof pitches, I'm thinking somewhere between 20 and 30 degrees makes sense. Does that seem reasonable?