Mortal Kombat 4 (Unl) is an unlicensed adaptation of Mortal Kombat 4 for the NES. Given that Mortal Kombat 4 was released after the NES’s peak, this represents an unofficial port likely developed by a third party without official approval from the original game's creators.  Details on specific developers or features are scarce.

Mortal Kombat 4 (Unl)

Mortal Kombat 3 - Extra 60 (Asia) (En) (Pirate)