I am a huge fan of Mortal Kombat and Mortal Kombat 2 is one of my favorite games of all time, so I have been following this project over the last year or so. Mortal Kombat 2+ is a fan project and isn't just a couple of balance changes or some kind of MUGEN fan game. This is a completely updated version of the original Mortal Kombat 2 arcade game that utilizes all of the sprites and code of the original arcade game.
Youtuber Paul Eicher has been documenting his progress on Mortal Kombat 2+ by periodically uploading videos showing off all of the additions and changes coming to the game.
He certainly has one upped himself this time as he has managed to add The Pit stage from the original Mortal Kombat into Mortal Kombat 2 complete with an uppercut into the spikes at the end. It's amazing that this is all being done utilizing the original assets from the arcade games and it looks a hell of a lot better than what we got in the official release of Mortal Kombat Trilogy.
For those who are interested, here are all of the additions being added to Mortal Kombat 2+