I liked the animations a lot! the music was great and fitting, besides the troops and zombies were the graphics good. I think a menu screen or start button could have been nice and the numbers on the upgrade buttons don't really tell you much. +5 attack would be a lot if the base attack damage is 1 but it might be worth nothing if the base damage is 50. Same with the health and attackspeed. I think some sound effects could have made this really satisfying. Overall really solid submission!