Just A Few Routes I’d Love To See In The Future, Or For The Longer Ones, Parts Of Them

LNER Azuma: Leeds to London Kings Cross
CrossCountry: Edinburgh Waverley to Penzance

And for a complete and utter longshot which I would happily buy in a heartbeat:

Trans-Siberian Railway: Moscow to Vladivostok

 

Leeds to London Kings Cross can be done in full and is available on ATS
https://alanthomsonsim.com/download...e-london-kings-cross-to-leeds-and-york-merge/

For Edinburgh-Penzance, it would be too long for one full route but can already be done in parts.

Edinburgh-Newcastle
https://www.justtrains.net/product/newcastle-to-edinburgh-download

Newcastle-York
https://www.dpsimulation.org.uk/ecmlne.html

Both of the parts above can also be done on the ECML merge on ATS
https://alanthomsonsim.com/downloads/the-east-coast-mainline-merge/

York-Leeds
https://alanthomsonsim.com/downloads/leeds-lines-phase-2/
Or
https://www.ontracksimulation.com/harrogateloop.html

Sheffield-Derby
https://www.justtrains.net/product/midland-main-line-sheffield-derby

Derby-Birmingham
Birmingham 2010 route by jetgriff https://www.wotawallysbits.net/jetgriff-routes.html

Birmingham-Bristol
https://alanthomsonsim.com/downloads/xcroute-birmingham-to-bristol/
Or
https://xcroute.com/extended/

Bristol-Penzance
https://www.justtrains.net/product/western-mainlines

With the South Devon Mainline and Cornish Mainline extensions, you'll finally reach Penzance.

EDIT: Glad I wasted my time doing this......

 

It is appreciated. Thank you for posting the list. I have all of those myself (except the ECML Merge) but haven't installed XC Route, Birmingham 2010, Harrogate Loop, or even Midland Main Line yet, but I wlll eventually work my way along the line myself. Maybe one day we'll get the Leeds to Sheffield section, too.