GONK-18 is a fully automated sentry tank encountered by a Western military squad during cleanup operations in a ruined city after World War IV. Originally deployed by Eastern forces, this autonomous weapon remains functional long after its creators abandoned the area. Its designation comes from the distinct mechanical noise ("GONK") it makes during operation.

Physically, GONK-18 is a quadrupedal robotic vehicle clad in heavy armor plating and boasting integrated advanced weaponry. Its armament includes high-powered laser cannons, missile launchers, and explosive projectile systems. The design prioritizes durability and firepower, enabling simultaneous engagement of multiple targets. Comprehensive sensor arrays provide battlefield awareness, allowing efficient tracking and elimination of threats.

Operational behavior strictly follows programmed combat protocols. It identifies and engages armored military targets with lethal force, demonstrating tactical adaptability by using urban structures for cover and deploying drones for missile attacks. During confrontations, it exhibits a distinctive characteristic: upon confirming an opponent has discarded weapons and powered armor, it ceases hostilities and verbally acknowledges the disarmed individual with the phrase "Farewell to weapons." This indicates programmed recognition of non-combatant status.

Its combat effectiveness is demonstrated during engagements within city ruins and an abandoned subway system, where it systematically destroys powered armor units. The tank operates independently without external command, suggesting advanced autonomous AI. No modifications, alternate versions, or background developments beyond its 2013 animated portrayal exist in official media.