Factorio Forums

I was writing this so I can refer to it when someone asks why I don't include full support of multiple forces in my mods.

Playing with multiple forces allows for some hilarious hijinks. Especially when trains are involved:

• Different forces can easily render tracks inoperable by placing signals or rail segments.
• Naming stops the same across forces results in randomly confused trains.
• Connecting wagons and locomotives of different forces is possible.
  Even forces marked as hostile have no problem stealing a train by attaching their locomotive to it.

Attaching tracks and signals to other forces as well as connecting rolling stock of different forces should only be allowed between friendly forces, if at all.

I suppose that's working as intended. If you let a hostile player come close to your rail network, why shouldn't he be allowed to mess with it?