My post is related to the ones of LocoMH and Neihgborkid but you didn’t get my point.
You pay for MMO’s mainly for the server infrastructure, because thousands of players play on one server and for Game Masters and so on.
But nothing like this is needed in a MP for a tycoon simulation.
So making the players pay for a MP in Train Fever would be a horrible idea, since this would just look greedy and would deter the community.
It sounds to me like a subscription model what you’re suggesting but maybe I missunderstand you so please clarify what you mean.