A very god idea, even if the game loop wasn't obvious, the construction and train systems are so fun and addictive that had me hook to the game even if i wasn't trying to complete and objective. Nice job.

It looks like a good base for a game, but is missing a gameplay loop. Make sure you plan how the basic loop works (and in this case is doable in the given time) when starting a project! But still, good job! :)