It's loosely based on a 6-station stretch of the Fuji Kyuukou line in Yamanashi. Not sure my environment art really did the real life area justice, but that's how I derived the stations and spacing between them. https://en.wikipedia.org/wiki/Fujikyuko_Line
That's exactly right. The issue I ran into is that the Playdate's CPU doesn't have a lot of juice, and spends a lot of time every frame just filling the screen. There's no specialized blitting hardware or GPU. Hence realtime sprite scaling is not feasible.
I tried making some pre-scaled sprites, and the ROM footprint had to be pretty large to afford enough size steps for reasonably smooth motion as the train moved past objects. Even then, all that sprite drawing was starting to dip the frame rate.
So, I experimented with a pre-rendered approach, and that was a huge unlock. Eventually I was able to wrangle it into something that I think worked even better in the end! The pre-rendered video based approach allowed way more elaborate detail and I didn't have to worry about frame rate anymore.
I love Densha de Go. DDG Final is one of my top 10 fav games of all time. When I got a Playdate, I had a vision of using the crank as a train's master controller and I was compelled to see it through...