Taking what is often a "horde" army and making use of a small section of them is a really neat idea. I love the individuality put into the rats as they face their foe, and showing them at the start doing something more menial than just fighting. The theme really shines through, and I finished the story trying to work out who was the intelligent one and who was relying on strength more but in a good way, with the twisting of the two concepts in both foes.