From the 2007 announcement that our studio is building a new version of Train Simulator:

...this version will be an all-new product built on the Flight Simulator X platform, the culmination of 25 years of product development and technology.

Sounds great, but what does it mean?

"all-new"

By "all-new" we mean that we've started from scratch with our Train Sim development.  We're not using any code, art, route data, world data, textures, cabs, or rolling stock from Train Simulator 1.  It's not that we don't love TS1 or think that it's a great product.  We do love it and it is a great product.  Just look at the passionate community still active these many years later. 

But the computer gaming world has changed a lot since then.  For a little perspective, at the time TS1 launched:

• The Pentium 4 was the newest advance in processor technology. Forget Hyper-threading, let alone Dual Core.
• Windows 98 and Windows ME were still the dominant operating systems.  XP hadn't yet launched.
• DirectX was at version 8 (with Vista we're now at 10).
• NVIDIA launched the GeForce 3.  Huge advances in GPU technology have evolved in the generations since.

It just didn't make sense to try to update TS1 when so much had changed.  We're also not using the code from the original MSTS2 that was eventually cancelled.

"built on the Flight Simulator X platform"

As we strived to bring back the Train Sim franchise, we looked back to understand what caused us to let down TS in the first place.  One factor, though not the only one, was that the Aces Studio found itself in a position of having to maintain three separate sets of code---Flight Sim, Train Sim, and Combat Flight Sim.  There was little-to-no sharing of the code between these three products, and that turned out to be a big problem for us.

The reason is that a chunk of code is the beginning, not the end, of development.  It needs to be tested.  It needs to be localized.  It needs to undergo security and Trustworthy Computing reviews.  It needs to be tuned for performance.  In short, it needs to be cared for.  That takes time and people, and we didn't have enough time or people to tend to all three (completely disjoint) sets of code, especially when much of the code was just different ways of doing the same thing ("redundant" in dev-lingo).

So we made the painful decision to let go of two (CFS and TS) so that we could focus 100% of our attention on making the remaining one (Flight Sim) as magnificient as possible.

"the culmination of 25 years of product development and technology"

Even when that decision was made, we knew that we didn't want to be a one-product studio.  Everyone involved believed that in Flight Simulator we had something very special.  How many games can you think of that have been in successful development and release for 25 years?  You won't need more than one hand to count them on.

Because of the way Flight Sim had been designed and built, we knew it had the potential to become the foundation upon which we could build any simulation we want.  With Flight Simulator X that potential can now be realized.

Shawn Firminger, our studio manager, deserves most of the credit for crafting a strategy around turning the Flight Simulator application into a generalized Simulation Platform.  His message was simple and powerful---if we take this 25 years of sim technology that's in Flight Simulator and refactor it to make it easy to build new simulation experiences on a common base of functionality (for example: object rendering, scenery, buildings, autogen data, landclass data, AI, animation), then we can have our cake and eat it too---we can build lots of cool games and we can care for them without having to greatly expand the size of the studio.

With this strategy in place, bringing back Trains was a slam-dunk (easy for me to say---I wasn't here at the time).

When is "all-new" not all new?

So, yes.  The new version of Train Sim is "all-new," but at the same time it's not.  It's got the DNA (and much of the actual code) of one of the most successful, enduring franchises in computer gaming history---Flight Sim.  That's why we're totally thrilled to be rolling on Train Sim once again.