Fat Beam

While this is not the final naming, I feel "Fat Beam" describes fairly adequately this huge beam attack that's larger than the weapon's muzzle - and which gets larger as you level your weapon power.

It's surprising how much trouble this weapon gave me, considering how simple it is.  While I would have estimated the lightning gun would give me trouble, I programmed that weapon in a single day; the Fat Beam, on the other hand, took me a full week.