Author here. Trail Router is a running route planner that prefers greenery and nature in the routes it generates, and biases against busy roads. It can generate round-trip routes that meet a specified distance, as well as point-to-point routes.

I've written a detailed blog post about how Trail Router works here: https://trailrouter.com/blog/how-trail-router-works/

I developed this because I am (or was...) a frequent traveller for work, and I like to run wherever I visit. But I don't enjoy running on busy main roads, and I found that without careful and time consuming route planning that is often what would end up happening if I didn't know the area. Trail Router is my solution to this problem.

After a previous discussion (https://news.ycombinator.com/item?id=23177351) received quite a lot of attention, dang reached out to suggest I post a Show HN to reach a wider audience. I've addressed some of the original feedback too - for example, you can now prefer hills in your routes, as well as avoid them.