Gauntlet (USA) (Unl) likely represents an unlicensed or unauthorized version of the NES Gauntlet. 'Unl' suggests it's an unlicensed release, often meaning lower quality or unauthorized modifications from the original game. The nature of these unlicensed games varies greatly; some may be simple copies, while others may feature modified graphics, gameplay, or even entirely new elements.  Without further specifics, it's challenging to define its development.

Gauntlet (USA) (Unl)

Gargoyle's Quest II - The Demon Darkness (Europe)