Nice idea, I only player single player but it was fun taking turns with the CPU. It was fun once it got going fast and not too difficult.
I wish that I could place pieces more ahead of time; it seemed to only work when the train was very close. And sometimes a piece didn't place at all which was frustrating. Also I kept getting confused about whose turn it was; I believe the little levers on the side indicate that but they're too hard to notice. Something more obvious that it's my turn would be good. And I'm not sure the passthrough adds much gameplay-wise but it is kind of cool having your train track in your living room.
I love that I can pull the whistle.
Thankyou for making a Pico version! That allowed me to play it with passthrough.
(I tried recording a video for you, to return the favour, and I did, but it didn't record my microphone so there was no point uploading it.)