There is some different plasma guns used in games, some of them are rapid firing and some others have a more moderate rate of fire, those weapons have a certain level of power, and sometimes they have a splash damage Quake 3
's plasma gun for example have a small splash damage area; the Deus Ex
Plasma rifle in an other hand shoots 3 plasma Bolts, some other games like Doom
or Unreal tournament
doesn't have any splash damage.
Those weapons aren't well suited to be used against fast moving targets due to the bolt's speed, but their rate of fire allow to confuse the enemy