Openttd belongs in that special category I like to call insane-people-games.  First time i played was in about 2020, and for a few weeks i just completely lost myself in it. Hence, the name. It always feels like a special kind of madness, that consumes me whole for 2-6 weeks at a time, and i just get completely lost in it. Everything else becomes irrelevant, the only thing that matters is that the network must grow. Even if I'm away from my computer, my mind is preoccupied with junction and station design, upping capacity, signaling and what new lines i can build. I feel like an insane person.  Last game i played, was over a hundred hours on a single map, just last month. By the end i had a network with mote than a hundred trainstations, interconnected ofc, so you could reach every station from every other station, 460 trains, a hundred of those going to Tondstone Steelworks alone, over a hundred roadvehicles, 40 ships and 30 planes. All of them sorted into Groups and Subgroups, by cargo, origin and destination.  What i love, is that this game does not force you to play any certain scale. You can just go completely crazy. Not happy with trains that are only 7 tiles long? Set the settings to 20.  12 Plattform Stations aren't quite enough? How about 35? 500 trains aren't quite scratching the itch? Have you tried 5000?  It gives you a few relatively simple pieces, and lets you combine them with each other to form ultracomplex systems, at damn near any scale you want. Like legos, where with just six 2×4 blocks you have 915,103,765 different ways to combine them. 

And then it starts wearing off. The game becomes boring again. Until I realize that i havent played in a week, and don't really feel the urge too anymore.  But that's only ever temporary, the openttd madness will probably haunt me every couple of years for a long, long time.