My game called Fragile route was a submission for one jam, and was in demo. I made a full postjam version of the game, where all the content I wanted was finished.
In short: the gameplay of the game is to build cars for your train. You have a list of materials that you mine and use for building cars. There are 3 chapters in the game, and the goal of each is to build a final car for that chapter.
The plot of the game you can learn in the game itself.
https://topazich.itch.io/fragile-route
