You are the ultimate vaccine. But, to get stronger, you need to eat as many baddies as possible. Use your ARROW KEYS to move. Shoot enemies to make them shrink. Hold "D" KEY key to shoot. When the enemy is small enough, you can eat them. Get close to the enemy and press "S" KEY to eat it. Eating also fills up your power bar. Hold the secondary fire key to charge it up. Press "A" KEY to fire secondary weapon. Fill the bar 3 times and your firepower increases. The bar at the top shows how much you have eaten so far. The bigger it is, the more you will grow.