You are the sheriff of the veins and blood vessels of a person. Your duty is to help its heart.
Use the arrow keys or WASD to move around and configure your bazooka.
Use J to shoot white blood cells and kill bacterias and K to shoot red blood cells and grab oxygen.
When bacteria hit a vein wall they weaken, use L to shoot platelet and prevent them from breaking.
If you do this right, oxygen and health bars will maintain steady and you will help the heart.