The game is flowing inside the body of a critically ill patient. You as Bactron - a yellow blob of antibiotics - should reactivate the enzymes which have been sterilized by the viruses spreading within the body. Exploring the area representing the body you should move from one screen to another using certain doors, solve the labyrinths, push/pull obstacles to move further, avoid the viruses which will drain your energy if you touch them, spit at them to make them frozen for some time, locate the enzymes in the patient's body, and activate them. You should be quick, because more viruses are being produced and the patient's temperature is rising. The enzymes are shown as yellow cubes, and activating them boosts Bactron's energy, but don't touch the light blue cubes!