SF4 Gas

The Sulphur Tetrafluoride Grenade, or SF4 Gas for short, is a secondary upgrade for the shotgun. The grenade flies in an arc before exploding into an expanding cloud of gas that lingers as it dissipates. The gas will injure anything caught in it, and is not affected by wind or pleas for mercy.

Whereas explosive weapons can shred enemies in an instant, the SF4 grenade adds a new dimension to the grievous harm you inflict on other lifeforms - time. The gas needs a little time to spread before it becomes dangerous, so you have to anticipate where your enemies are going to be. This makes it a little harder to use than your fragmentation grenade, but the fact that the gas lingers for a good few seconds opens up more tactical possibilities, and it can be even better than a grenade at thinning out a crowd of baddies who are trying to rush you.