Killer atmosphere and animations.
Looking at stats.fnl helped me understand the mechanics. Your units are goblin, demon, skely, and hood, and they all have different amounts of HP. They can be armed with basic, bow, wand, knife, or halb, which can be melee or ranged, have different ranges, and do different amounts of damage. So I guess some basic strategy is to use you melee units up close to hold the humans in place while your ranged units do damage from a safe distance.
I don’t know if it’s the canon interpretation, but the final battle being in the same map as the shop made me imagine that I was now fighting the shopkeeper who had secretly been my enemy all along.