Found: Mystery, fictional warfare (recent)

This book was written quite recently, I believe in the past six years or so. The book is about a boy in a futuristic America that is broken up. Much of the book focuses on a unique attack style where drawing shapes and patterns on the floor with chalk can animate and attack physically. He goes to a school to learn this and meanwhile there are mysterious murders and a war going on that utilize this form of attack. I believe the book cover is red and has a metal horse. I'm pretty sure the title is a single word. The book also has the futuristic map of America and several drawings of patterns and shapes. Thanks for the help!

The Rithmatist by Brandon Sanderson?

Yes, thank you.