My guess would be Mac as they have dabbled in it before (and if I recall actually got Trainz working on a Mac (and not boot camp). So 'updating' it would probably be much less work then re-writing it for a different platform.
If a good hacker wanted to (and assuming it is for the mac) it is possible to get Mac OSX programs working on linux. Or at least it is much easier.
peter
I'm a Mac head but I don't see it going that way. The two OSs have been growing closer than further apart. I didn't get into Macs because I hated Windows, I hated the idiots in their Mom's basement handing out viruses as a way getting even for other lackings. At least the crooks I could understand, it wasn't personal. Once any OS gets popular, the hackers will follow. Every time someone knocks Macs I think "YES", keep the hackers away, not the users.
All these OSs have become bloated. I loathe Mac 10.5 but liked 10.4. No bloat ware. All the needed security problems have made them that way. Tired of all the needed patches and resources needed to counter all of that.
I have been running 2009 on a MacBook Pro with an Intel core duo 2.16 processor, 2 GB RAM and 256MB ATI x1600 video card. Even with that in windowed, compatibility mode I get 30 to 60 FPS. The secret, no anti virus safety programs since that partition never goes on line. It's all that is running.
With all the hackers and thieves I don't think any program, especially a game, will ever be able to perform. To many resources lost keeping them out. A console would be the way to go but even those are starting to become reliant on the WEB. Reliance on the WEB for DRM and even DLS access will keep pushing system requirements up to keep the hackers out.
To much personal info and business transactions are online to keep anything safe.
Dave......