Atmospheric Composition Setting in PlanetStudio where will be gases like:
Oxygen - Drood Friendly, but much of this gas can kill them. Also makes jet engines burn.
Nitrogen - Droods needs this gas too.
Xenon - Noble gas. Do not burn.
Sulfuric acid - Damaging rocket engines
Carbon dioxide - Do not burn.
Carbon monoxide - Killing Droods without spacesuit
Steam - Brings summer sale)
Undefined gas - Do not burn. Killing Droods without spacesuit. Prolonging RTGs working time.
Darkium - Destructs any craft that entering an atmosphere.