Pathfinding can be exploited for cheaper costs.

[ChristianNoelSchmid]

Being able to create a track from anywhere allows players to arbitrarily create tracks. With this in mind, I can build from a medium city to a clear node, and only pay the clear node price. Either we need to ensure that players can only build from Major cities / tracks they already built, or we need to adjust the pathfinder to automatically accommodate for this kind of system-gaming.

[thomabel]

We need a path validation algorithm to catch these sorts of things. One that checks that all newly built track either

A: is connected to a major city or B: is connected to that player's already existing track.

That should solve the exploitation of building from a small/medium city.