One of my favourites! Especially since i know you diverted from the usual unity/unreal engine and use a custom javascript engine. That just makes it even more impressive. I looked through the source files and even though the math is often a bit over my head, it's still pretty clean and easy to read through.
The music is soothing and and still playing in the background while i type this. The art is amazing for something that was put together in 48 hours. The details on the train and the variety of items really give it a polished feel.
As for the way it fits with the theme i geus it is a bit open for interpretation, but that is not a bad thing. For me the duality part is the fact that the same item can be worth 10 dollar at one station, but worth 5 times more at the other station. So a difference in view of value. I'm not sure if this was your intention also, because i see soem other parts that could also be considered a duality.
Anyway! Well done, 5 stars because i had fun with it and it made me relax after work!