A lone crustacean vessel patrols the perimeter of an ever-shifting three-dimensional tunnel, tasked with intercepting waves of adversaries that emerge from its geometric passages while dodging the threats barreling back toward the rim. The tunnel morphs continuously through varied architectural forms, demanding constant vigilance and adaptive piloting as enemies pour forth from multiple corridors simultaneously. When overwhelmed, the craft can unleash a devastating superzapper—a temporary surge of destructive power capable of annihilating every threat currently occupying the tunnel's interior.