Like the art (especially the octokings), cool concept, I'd say these are the 3 direct things that could be improved upon imo:
- More of a tutorial, I had a few points where I had no idea what I was doing, e.g. I had clicked 'attack the king' thinking that would start a wave and then sat there defending because I misunderstood that I had to click that button
- The troops would really really benefit from a multiselect, like a click-and-drag select all feature from an RTS. I feel like the difficulty comes from having to micromanage all the commands if the enemies only attack one flank at a time
- Sometimes when the troops killed the middle units, they would start patrolling again and the edge unit would keep attacking and there wasn't much I could do about it (it looks like this was mentioned below as well)