As some of you may know, the next version of unreal tournament is being developed in the open with the fans assisting. Here is my take on the lightning gun!
The core concept revolves around two van de graaff generators which store their charge in magnetically levitated crystaline super capacitors, these electron filled balls are then magnetically propelled like a rail gun bullet. When they strike their target, the crystal lattice is broken and the charge is released, travelling back along the ion path created from its travel to the gun itself.
Net result is a lughtning gun that is accurate like a sniper.