I really loved the idea of a puzzle game together with being able to build your own train line, the feature of being able to upgrade the tracks by joining them was a nice surprise.
As a 3D artist on my team i was very happy to see another 3D game in game jam with an a retro theme, with so many games in pixel art, great job with the modular tiles.
With a few more visual polishes and a fuller UI it could easily be a successful mobile game.
To improve the ux, maybe give the player small hints of the differences between the dark green tiles that are apparently is on a high ground on the terrain.
Thank you for the pleasant surprise and congratulations to the developers :D
~Nicolas