I don't do Suggestion a lot but for new 3rd party devs before making routes in new ares it time to makes routes that we already route to link as there very big gaps for route hopping these routes are for DE and UK Route 1 Koln to Koblenz This route have great scenny to have Route 2 Koln to ever Duisburg or Wuppertal Route 4 Groningen to Oldenburg Route 6 Hamburg to Bremen
Route 7 Munich to Rosenheim would be for up coming rail jet Route 8 Route 9 Heilbronn to Mosbach or even Mannheim Route 10 Birmingham to Derby or Leicester
Route 11 Ashford to Eastbourne Would be great if any 3rd party devs make these routes to fill in the gaps
Chemnitz-Leipzig could form a triangle. Ingolstadt-Munich and Munich-Rosenheim are obvious ones but Munich is clearly an issue. There's also Wurzburg/Ingolstadt to Augsburg via Treuchtlingen but that's long. An extension of Main-Spessart at both ends would create a huge triangle. Been meaning to do a post about this actually. Mainz-Mannheim and/or Frankfurt-Mannheim would be an option, as would Mannheim to Heilbronn or even direct to Stuttgart. Lot of parallel railways in that area.
I kinda like Route hopping, but maybe we could get sth where you get the option to continue a service on another route (especially if it is literally the same timetable service) already loaded from previous part