Horrible Gas is a lethal killing thing that kills you on contact. In LittleBigPlanet , you can only pick 6 colors for the gas to be in the moon.
How to Make Gas Really Colorful in LittleBigPlanet 2
Go to My Moon, open your popit, get any material and place it. Now go to the tools bag, select the gas, and tweak it to any color and 10% brightness. (It looks like that in The Factory of a Better Tomorrow.)