Train Fever.
I had a couple "I have no idea what I'm doing" playthroughs that didn't last very long, then finally 1 long "This now makes sense" playthrough that lasted 1850-1965, and I recently started a new save, in which I can start planning everything from the beginning in ways that will make sense in later stages of the game.
Anyway, whenever I feel an urge to game, that save is what gets loaded first. I'll load it, maybe add a new rail connection between 2 cities, expand my existing network, add in an LRT line to a city, see where cities have expanded, expand my services accordingly, maybe add in a coal transport line, a goods line, etc.
It's an amazing game, once you figure it out. It's basically like transportation tycoon deluxe with better graphics and many other improvements.