I know that multiplayer has always been a hot topic in TSW ever since it released (looking at you @ryans#9175 ). But I do have an idea of a good way to go about it... Using timetables! The existing timetables have hundreds of different services, and normally all but one are run by AI at any given time. The idea I have is that to make this a multiplayer system, you'd connect to a server for that timetable, and choose an available player-controllable service to take control of. Anything that is not taken over will either not operate at all or be driven by AI. As a result every player contributes to operation of the route's timetable. To expand on this there could also eventually be player-controlled guarding and dispatching, making for more fun opportunities. (In the case someone blocks a signal for a while or is otherwise causing problems, they would be kicked.) This is a simple explanation I've given so I don't expect everyone to understand it the same way, but I do wonder how feasible this could be as I think it's not bad of an idea.
And then you have that one person who decides to just sit there and ruins it for everyone by making it so no-one else can move...
Well, to redesign the entire game to it can run multiplayer efficiently just for that. Well, I don't see it particularly worth the pain. Even in something like SimRail, I barely notice that I'm actually playing with other people. For multiplayer to actually be fun, there'd need to be a bunch more Tasks that can be completed by players in the server.
Why the sudden surge in MP threads? Has already been discussed that DTG see it as a low priority (or they would have done it by now). If SimRail and Run 8 are anything to go by it brings very little to the game over and above a decent SP game (my detailed views on that are in the other threads). There are far more pressing issues DTG need to sort with TSW before even sowing the seeds of any kind of MP game. Though having said that, there’s always the chance they will spring a surprise with TSW6 and suddenly announce it’s coming!
Most users are not asking for a multiplayer mode, but rather expect DTG to implement other features first. The most common requests are for Ebula, announcements, timetables that sometimes produce unexpected results, real passengers who behave like passengers, etc. And most users say they don't want a multiplayer mode; DTG should first get the core running properly and also address other issues that we have been experiencing for a few years now.
There are far more important things that need to be done before multiplayer is even considered. Then there's the fact DTG have outright said it won't happen.
At best, for those who actually want MP, one of these new IP's to be announced might be a MP spin off, possibly even subscription or pay to play based.