In X-Com: UFO Defense (Enemy Unknown), the first installment of the iconic X-Com series, the most common weapon used by the alien soldiers were deadly energy weapons that fired beams of hyper-accelerated matter, or plasma. These plasma weapons could burn through reinforced steel or titanium and disintegrate anything softer than the aforementioned alloys, like wood, cloth, or flesh and bone. These weapons use a highly-advanced Elerium-powered particle accelerator. The ammo clips they use are actually compact Elerium batteries that feed power to the accelerator.Plasma Pistol Plasma Rifle