Transport Tycoon Forums

Hey, could anyone tell me how to make an ai script or library like Pathfinder.rail.1

By looking at the corresponding articles on the OpenTTD wiki.

The wiki has a lot of information, see here: http://wiki.openttd.org/AI:Main_Page

You can also just extract some of the tar files you downloaded (OpenTTD can load them even if they're not packaged as tar) and see how those AIs / libraries work.