I tried the demo!
Art: Looks great. Like the macabre theme.
Gameplay: Pretty good so far. Didn't like how barracks do nothing if their target is destroyed... I ended up just targeting the castle so I didn't have to keep re-choosing targets (and sadly that worked better than worrying about micro-ing them).
Tutorial: Good. Only thing that wasn't clear was capturing Crystals. Had to play it a second time to get that putting a fence around the crystal meant "capture" - but still not sure what benefit they give.
Favorite part: The campaign map.
Top request: Wish there was a more clear visual when you choose an invalid target with a barracks (like a crystal or empty hex).