Perhaps what Civ VII 'needs' is a class of Negative Unique Units - unique units from history that were total failures but so distinctively bad that they deserve to be inflicted on a gamer or AI.
Off the top of me head examples:
I-400 and Surcouf, as discussed
The Roman anti-elephant Flaming Pigs (that were an absolute Requirement in any miniature Roman Army back in the 1990s!)
the Fairey Battle aircraft - an attempt to use a heavy bomber defensive turret in a fighter plane, resulting in a fighter with no speed, no maneverability, and no chance of surviving a mission.
CSS Hunley - which sank itself three times while sinking one enemy warship, probably a record among historical Kamikaze missions.
The Davy Crockett - US man-portable tactical nuclear weapon, which could spread radiation further than its launcher could fire: a 'one-shot' weapon, especially where the survival of its own crew was concerned.