It would be great if there were some EU cross border routes, where players get to experience either hauling passengers on cross border commutes, or euro rail freight. This would be quite a unique experience compared to a lot of content out there already. Hundreds of thousands of commuters in the EU make cross border commutes every day, so this would provide quite an interesting experience for North American and other global players to see. The Grand Duchy of Luxembourg would be a great setting for this. Its a country of 600,000 residents, with another 200,000 commuting in to the country each day for work from Belgium, France and Germany. Luxembourg station has connections into France (including being connected to the TGV Est line to Paris), Belgium and Germany, and services that go as far as Switzerland. There's a euro multimodal rail freight yard in Bettembourg for freight scenarios. Additionally, it has some interesting new stations like Pfaffenthal-Kirchberg, which serves the one of the EU's three de facto capitals. I really think a cross border DLC centred around Luxembourg could be quite a unique and attractive offering.
