They've ruled out hitchiking. Which is a shame, because I'm reminded of the 'Jailbreak' charity fundraiser, where students are challenged to get as far as possible [with sponsors paying per mile] from their starting point using only transport offered for free. Some of them managed to persuade airlines to give them long haul flights...

> The transport must run regularly, not just as a one-off event.

> You cannot walk for more than 500 meters at a time to switch between two stops.

Edit: plenty of the other rules outlined would rule out hitchhiking

It is definitely possible to hitchhike with the rule of not walking more then 500 meters. Sounds like a cool game by the way! I loved hitchhiking with arbitrary rules, an entire continent becomes a playground.

Having read the rules, I do believe is is possible to hitchhike in such a way that it qualifies as free transportation that allows to travel the longest distance. A simple way to do so it to get a single ride that is several hundred kilometers long.

The author of the question on StackExchange accepted hitchhiking as a valid answer.