What if a gimmick Fps game where your only weapon is a single barreled shotgun, but you can get powerups that give you a "damage multiplier" in the form of actually being a BARREL multiplier which can keep stacking to nearly NIS levels of ridiculousness, but each additional barrel means extra ammo usage, additional physics pushback, AND additional damage potential due to how many pellets are fired?

Could be called "Superlative Shotgun"