I finally added the possibility to shoot holes in the landscape!

First I tried implementing it using the SmartShape2D addon for Godot that I was using. But I got a strange bug where the fill color would disappear when I tried to modify the terrain polygon on hit. The collisions stopped working as well. 

As I couldn't figure out what was going wrong, I finally decided on implementing the terrain myself using only the standard Godot components. I found a nice video tutorial that I could adapt to my needs and it all went surprisingly well.

As the terrain has no textures, there is basically just the green shape and the black outline. So, I had no real need for the smart shapes anyway.

I hope you like the update.
I think the terrain behaves a bit different than in the original, but I find it is fun, anyway.