Train or Rail based system and a couple minor ideas.

[Holodream]

Absolutely Loving this game so far and can't wait to see where it goes.
If i'd ask for, or suggest one thing it would have to be a rail based transport or cart system for the beavers to travel or haul resources with.
A couple other minor suggestions would be letting us fill a beaver made reservoir above 1 block of water.
And the ability to create underground systems or tunnels easier than explosives to remove a mountain and rebuilding it out of levee blocks.

[Torven]

The best way to implement this would probably be small hand carts, small enough that they could fit two tracks on a single tile. I don't see them implementing a new routing AI just for a rail system, and limiting it to one cart between two stations wouldn't be worthwhile, so they'd need a system where the carts could pass in opposite directions on the same tile.

[Holodream]

I agree in that full blown trains wouldn't be the way to go, but something along the line of narrow gauge or mono rail type systems like that used in mining that can haul goods or transport beavers. Tom Scott has a great short video showing them off. https://www.youtube.com/watch?v=Irv3KJR6B80