Gametype:Chaos Theory
From #openttdcoop wiki
The Chaos_Theory Concept
By Gamer, updated by AntB
The Chaos Theory Concept is a difficult one to understand. Chaos theory is best described by one word: "random." Not much is known when we start building... only the train length and cargoes. Track goes where ever it can go when it's need and lines are expanded as and when they are needed.
The best way to get an idea of how Chaos Theory works is to download a save and have a look yourself.