The original is a masterpiece when it comes to programming and UI design I think, at least for it's time. It is also very fun :)
It's very nice that it is kept alive in this fashion with openttd.
You needed to be in a more focused state of mind and had much more patience.
Also, a lot of what TTDPatch and then OpenTTD did was just expanding what could be done purely as function of computers having vastly more RAM and much more graphics compute power. More trains, bigger maps, better use of the 256 color palette, eventually supporting 32 bit rendering entirely, adding modern polygon billboarding for sprite rendering, etc, all things Chris would have done if the was still making games like that today.
Chris quit the industry and went to go enjoy life instead, and his company just manages the rights and does ports of the existing titles under new publishers to new platforms.