> Some years ago I tried it and found that it is quite easy to reach a state where there is too much clashflow, post that there isn't much of a further challeng

> Some years ago I tried it and found that it is quite easy to reach a state where there is too much clashflow, post that there isn't much of a further challenge? Is that still the case? Yes, it's reasonably easy to generate huge ammounts of positive cashflow, but if you find that bad, you can just give your money to other players in multiplayer, raise and lower sea, or bribe a random town authority until enough money vanishes. > the historical drop in rail passenger traffic in 20th century This happens in the OpenTTD too if you start offering non-rail passenger transit. > important choice of diesel vs electric You can enable this in OpenTTD options, but it's mostly a very easy drag-select to simply update your entire rail grid to catenary powered ones. The most important rail infrastructure decisions are between conventional/electrified rails, monorail and maglev, that requires actually replacing all your rails/stations/depots/trains infrastructure in one go. > and of letting other companies run trains on your tracks etc? Under normal settings, tracks are unfortunately too cheap to lay, you can just lay your own parallel set of competing tracks while leveling half of the land in the process. Another possibility is multiplayer, with several players on the same game company.