You are a Gas Mask trying to catch viruses before they take over the world. You have to chase viruses, and if you get close enough to them, you will be able to catch them. For this, you will get points, and the time to destroy the world will increase. But be careful! You may come across a Royal Virus that will break your filter if you try to defuse it. As long as your filter is broken and you don't find a new one, you can't catch anyone, and viruses will start taking away your HP if you get close to them.