For the curious, MSTS does indeed install and run on Windows 10.
Tested on a Core2 Duo laptop with Intel Mobile 945 graphics. (Yes, it's an old machine, but Windows 10 installed and runs surprisingly fast on it.)
I installed from original disks, using the normal process on Steam4Me. Some notes:
- Disk 2, which has gotten reports of problems in recent years, installed flawlessly. In fact, the disk spun up to full speed and stayed there for the rest of the install. Under Win7, the disk would only read at a very slow speed.
- Steam4Me process recommends using TweakUAC to put UAC in "Quiet" mode. The updated version that supports Windows 8 also works fine in Windows 10. Steam4Me site has a link.
- I ran the official MS update and content updates as usual on a new install.
- I ran the DirectX Redistributable from Micorosft -- this drops the complete DX9 & legacy support libraries that are newer than what the MSTS installer drops. Don't expect a modern MS OS to have all of them -- Win10 focuses on DX10, 11, and now 12.
- Set MSTS shortcut to "Run as Administrator" (Don't forget this!)
- Ran MProfile.exe to be safe. (It runs directly or from Launcher.exe just fine.)
- Ran MSTS. (Intro movie popped up an ran fine, annoying as ever...)
- Went into settings, clicked button to reset key layout to defaults (just in case...) and maxed out all sliders for sound and video.
- Ran a train in explore mode on default routes. Everything worked! Although the primitive graphics on the default routes hurt the eyes...
- Upon closing MSTS the first time, Windows popped up a message to ask if the application ran OK or not. Click option that it ran OK, and it won't come back again.
- Copied my backed-up full MSTS installation, complete with BIN patch and modern content and over-wrote the fresh install, then re-ran MSTS. (Tested Surfliner 2 and Monon routes.) Started up and ran fine!
- Route Editor and Activity Editor launch with no issues.
- Frame rates look the same as they were on the same machine under Windows 7.
Don't be alarmed by the "Program Compatibility Assistant" message that pops up after closing MSTS on the first run. Just click the option that it ran OK and it won't bother you again. I noticed it returned the first time I ran another instance of MSTS for a mini-route, so it may appear one time per instance of Train.exe if you have mini-routes. Not a big deal, really. Just feed Windows what it wants to know and it will stay out of your way.
Your mileage may vary, but it looks good so far!