The game is very pretty. The music is cool and the theme and esthetic are very good. The lore bits are awesome are really sell the atmosphere of a decaying world.
The number that increases (speed) is very low, (almost always below 1 km/h), which feels very slow for a train and it increases linearly, so the distance increases quadratically. This is very slow growth for this type of game and does not produce the enjoyment of number go up very fast. Moreover, this speed feels in conflict with the lore.
Religion and Dark arts are useless, so you could cut them to focus on the train and the upgrades. You could have used more images for the different parts of the journey of the train (maybe use AI to generate a few?).
The rhythm is slow as you need a lot of health to get to the end.
I would love to play a full version of this game where more time was put in development as I really enjoy incremental games with a detailed narrative.