Dirty Thunderstorm or volcanic Lightning

http://io9.com/387860/when-volcanoes-spew-lightning/<br /><br />Use this in your next game:<br /><br />Its not the lava the PCs have to worry about but the thunderstorm like effects, ash, rock and lightning from the skies. Rescue the colony, complete the corporate espionage, or whatever the current job is and get out.