Harald Hardtooth is a tooth with a face, arms, legs and a bowtie, armed with a tube of toothpaste. He must use this toothpaste to shoot all manner of bacteria enough times to kill (erode?) them. The levels are made up of a sequence of platforms, which run across most of the level. Harald Hardtooth can always jump up one level, or jump down as far as necessary to reach the next ledge under him without incurring damage, although falling off the bottom of the level costs you a life. Energy is lost through contact with the bacteria, and you have a limited supply of toothpaste, with a need to collect more as the game goes on. You can also collect enhanced weaponry such as double firing.