I’ve played quite a bit of OpenTTD. I spent a couple of evenings playing multiplayer. This was practically just playing together in a sandbox, not trying to compete or anything, just building stuff and chatting.
I have also definitely played on my own and with OpenTTD’s better tools for building tracks, signal posts and what not, tried to build rail systems that can handle multiple trains. In the original, I always build one track per train, I could never get it to work otherwise.