Best way to structure project where code is also used outside Unity

We're making a very simple turn based RPG

We have the game simulation implemented as a .NET class library

The simulation defers IO and rendering to Unity, but we also implemented the IO and rendering layer as mocks for unit testing, and we also have a console application that implements IO and rendering using ascii roguelike style graphics

In our previous project where we needed to reuse code outside of unity, we had separate solutions and had a build step that deployed the class library DLL to our Unity project folder

However it's much easier to work with code in Unity than it is to work with a DLL - how would we best structure our projects so they can share the same simulation, but also have the advantages of the simulation code living "inside" Unity?

 

I haven't tried it, but you could have your shared code as a git submodule. That should, in theory, allow you to share both code and changes between the console application and the Unity game.

 

OK, that looks like it might work, will look into it. Thanks!