Not RTS, but certainly real time, and as old as the hills.
Railroad Tycoon
The sequels never really did it for me. Transport Tycoon sucked up the hours, but nothing really did it as much as the feel of that first game. Maybe it was the time — the CGA monitor (which couldn’t cope with Civilisation), no mouse of course. I did play it years later and it want the same.
I doubt that feeling can be recaptured. It probably never existed - its a sepia tomes memory of a feeling from a different time with different expectations - but for some reasons the original Railroad Tycoon really stuck with me.
I think this is a common enough sentiment. Your first games leave more of an impact and that feeling is often not really related to how good the game is. Just like comfort food, they're comfort games.
I never player Railroad Tycoon, my first in that genre was Transport Tycoon Deluxe, but I feel pretty much the same way about it, and I'm pretty lucky that OpenTTD exists.
Similarly there's a game called Star Reach (also known as Space Federation) that was the first strategy game I played. In retrospect, it was pretty bad, but sometimes I want to play a space game and not even much superior games like Masters of Orion or more modern games like Sins of a Solar Empire will satisfy the particular craving like Star Reach.
Playing TT the first time, was the second time of my life I've ever done an all-nighter. I think I must've been 13 or 14 at the time. I'd only realized how much time had passed when my mom walked into the room at 6AM in the morning.
Then I was lucky to find TTD on some abandonware sites, shortly thereafter, the first TTD-Patch became available, and a few years later OpenTTD development started. I still remember playing it on a Nokia 5530 XM, they had actually ported it to the Symbian OS.
A few years ago, I learned that Chris Sawyer had programmed the entire thing in Assembly. It ran super-smooth on almost anything.
If you're looking for a modern derivative of Railroad Tycoon, you may enjoy Transport Fever. You'll find its demand-driven economy familiar, and staying solvent in the early game is tricky. Fever places a bigger emphasis on terrain—managing grade and turn radius to improve the speed (and profitability) of your vehicles.
The map missions in Railway Empire make it a lot less like Railroad Tycoon than what I'd want. What really made RT great was the open ended ways to succeed, while the very focused missions in RE too often forces me to build specific things in specific order. I really miss the freedom the map objectives in RT3 gave me.
That said, it is a great game and it is one of the highlights of the railroad-building genre.
Railroad Tycoon
The sequels never really did it for me. Transport Tycoon sucked up the hours, but nothing really did it as much as the feel of that first game. Maybe it was the time — the CGA monitor (which couldn’t cope with Civilisation), no mouse of course. I did play it years later and it want the same.
I doubt that feeling can be recaptured. It probably never existed - its a sepia tomes memory of a feeling from a different time with different expectations - but for some reasons the original Railroad Tycoon really stuck with me.