Consider toning down the motion blur for the title on the spine. I also feel that the 3 and Halo title blend in a bit too much. A rule of thumb i was taught was if you squint and can't differentiate between several (in this case two) graphical elements, then something needs to be fixed. Maybe try deepening the hue on "Halo".
Overall i'm looking foward to seeing this completed. Are you going to submit it as a 3D box?