upgrade mode?

well idk the name for this but a couple games have it.

its like a FFA and everyone starts out with a pistol and when you get a kill the gun upgrades so its like

start with m9 kill someone and u get a colt, then a duel colt, then anaconda, then deagle, then uzi, then mp7, then mp5, then m16, then ak74, then ak47, then m4a1.

or something like that.