Use the WASD keys to walk and the space bar to shoot. You will shoot in the direction of your mouse. There are occasional bandage boxes when you take damage. Don't touch the zombies. When you start flashing that means you have been touched and have invincibility for 4 seconds. You will also lose a heart. Press e to hollow blurple. Boss fight at 500 score. broken though.
This is my first game, so it is lousy but I think its pretty cool. If you are too close to the zombie the your gun won't shoot, but you will have to be very close to a zombie for that to happen, so don't worry about it.