Thanks for the feedback!
As for unit graphics, it's not my strongest skill so I tried searching for isometric people/unit/vehicle assets here on itch.io and other sites but couldn't find any that would fit with the style. I may have to just make them myself. If/when I do I'll be sure to release a pack.
I would suggest ripping the models from Age of Empires II, and then painting your own units in this style over those units as a base in their already isometric poses, it would be much easier, and would probably create the best looking isometric assets that have ever existed, if you could manage to make even just one knight and one wizard, people could start making really interesting games. However, each character is a lot of sprites with their animations. Bare minimum would need a walk/attack/die animation in 2 directions.
