The series has done so much over the years, but the only narrow gauge route has been the Arosa line. While I personally don’t have the DLC, it seems to be pretty great judging by its trailer. Narrow gauge routes have a lot of potential to be an enjoyable experience to explore. While I’m not thinking of any routes in particular, I’m sure that the Talyllyn, Ffestiniog, Snowdon Mountain, and Welsh Highland railways would make for great new content for TSW4. Considering Spirit of Steam was among the last routes for TSW2, I feel that you have adequate experience recreating steam traction. All I ask is that you consider my suggestion.
Still hoping for the Durango & Silverton, Cumbres & Toltec, and White Pass and Yukon routes. Ffestiniog would be awesome, too. Another line that would be cool is the East Broat Top in Pennsylvania. In former East Germany, there is the Harz Narrow Gauge, which I would like to see in game as well.
Would love to see the Bernina express in Switzerland or the Glacier Express. But both are much longer than the Arosa line (travel takes 3-4 hours for Bernina and more for Glacier express) even though the speed isn't that high.
I'm trying to understand why you're suggesting narrow gauge routes, while you don't own the only narrow gauge route available, especially since you say its trailer looks nice. If you want to support narrow gauge routes, why not do so with a purchase? That way DTG and third party developers know there's a real demand for these kinds of routes. In the end, these companies need to make money, and can only develop routes they're confident will get enough sales.
A combined Ffestiniog and Welsh Highland would be the grail for UK NG. And as being aired in another thread, something like the Wernigerode to Brocken section of the Harz Railway would be fantastic too.
That section has also really dense traffic. The summer schedule from Wernigerode to the Brocken: https://www.hsb-wr.de/out/pictures/ddmedia/325_Brockenbahn_ab_14.08.2023.pdf
How about Pilatus Railway and Achenseebahn in Austria and speaking of this its abt rack equipped like the Austrian Achenseebahn while Pilatus Railway is a Locher rack equipped.