The Denver and Rio Grande Western narrow gauge line ran from Alamosa, Colorado; to Durango, Colorado via Chama, New Mexico with branch lines leading to Silverton, Colorado; and Farmington, New Mexico. One of the most scenic stretches of track along the route is Cumbres Pass which is a 64 mile stretch of track going from Antonio, Colorado; to Chama. This entire stretch of track still exists today and operates as the popular tourist line, the Cumbres and Toltec Scenic Railroad. The line features many engineering feats such as Whiplash Curve, where the track loops back on itself 3 separate times in order to gain altitude. The line also passes through several railroad towns used as crew change and water stops when the line was still operated by the D&RGW. The locomotives used on the line are Denver and Rio Grande Western K-27, K-36, and K-37 class 2-8-2 steam locomotives built by the Baldwin Locomotive works (at the time of writing this, there are no K-37's in operation on the line) as well as a C-18 class 2-8-0 consolidation.The railroad also uses narrow gauge passenger cars painted in a Tuscan red paint scheme, although throughout the 70's 80's and 90's, the cars were painted green. The C&TS also uses restored freight cars that see occasional use on photo charter excursions. In the days when the line was operated on by the D&RGW, Antonito was the end of the line for dual gauge track on the railroad. The dual gauge ran as far north on the line as Alamosa. I firmly believe that this line would be a great addition to the Train Simulator store and hope to see this line in the future.
The Durango and Silverton has already been done by G-TraX at the D&S Historical Site. You can get it here -http://www.drhs315.org/blog/drhs-shop/ds-train-sim/
Train Sim's certainly lacking in the narrow gauge department. This would be a nice way to start remedying that.
You do realize that the D&RGW has the largest narrow gauge network in the US. Making an entire network like that in TS1 would be MASSIVE (in both file and memory size). And nearly all of them, now no longer exist. Except for both Durango & Silverton and Cumbres & Toltec that are still active as preserved, tourist lines (like the OP said).
Wow. I knew they had a narrow gauge network, but WOW. That's FAR more sizable then I ever dared to imagine.