Well done pivoting in 2 days on this!! I don't think I would've been able to do that much in that little time.
A few things that could probably be implemented easily is putting holes in your islands (to put water there), that way players would have to adapt to their environment to plan things out.
Another cool thing would be a task for each island e.g. "make at least two tracks that are at least 20 tiles long" or something along those lines.
Lastly, anything else to use money on! Maybe it changes the road look to be like a dirt rally, or lots of puddles everywhere, and these might simply increase the amount of money you earn from each track per second :)
Anyways looking forward to future updates!