Snail Shoot

Angry doctor decided to save our planet from humanity and developed a toxic gas which acts only on the people. He filled gas balloons and put them all into the air. Mankind is doomed and it would seem there is no chance of escape, but the very nature became our protection. A squad of fearless snails began to save us. Help them, starting the snails into balls. The collision with the ball, snails neutralize the gas.